Don’t lose ranking when migrating to a new website. Follow these 48 steps before, during, and after launch, and ensure your core websites pass with the Google search console.

WhatHowWhere
Select the best domain structureSecure related ccTLDs relevant to the geo locations that have been identified as offering potential. Consider also grabbing and parking on variations of your brand within related geo-locations.
Secure related social assetsEnsure all social assets related to brand are claimed.
SSL Certification SettingGet, configure and test the TLS certificate using SHA-2 for SSL.Server
Current site crawling - with design impactCrawl the site to identify and fix any internal broken links & the current Web structure before moving. Ensure links between all ccTLDs are in place to encourage crawling. Ensure no forced redirection is applied to users - instead allow interstitials to support user wayfinding. Ensure a universal footer that contains clear links between each site ccTLD type.Stage Environment
Localise site content before moveI.e. as needed;
Store locations
Meta content
Navigation
Images
Currency conversion
Phone numbers
Emails
etc.
Stage Environment
Google / search engine crawlingEnsure site does not block Googlebot appearing from the US, Google will simply not be able to access your content.Stage Environment
keyword researchComplete keyword research and apply to site pages along with forward content planning.SEO
New Web setting w/ updated internal linksSet the new Web version to make the changes, test & update the links on a stage environment, to point to the URLs (pages & resources such as images, js, pdfs, etc. too) with correct GEO reference and cross referenceStage Environment
New XML Sitemap GenerationGenerate a new XML Sitemap with the URLs to be uploaded in the HTTPs NZ/Int Google Search Console Profile once the site is movedXML Sitemap Generator
Robots.txt preparationRefresh the robots.txt setting in the new domain with the relevant changes and ensure major bots e.g. Google, Bing etc. are not blocked from crawling site pages, JSS, CSSRobots.txt
Campaigns updates preparationPrepare changes on any ads, emailing or affiliates campaigns to start pointing to the URLs versions as needed when the migration is doneCampaigns Platforms
URLs Parameters ConfigurationIf URLs parameters are handled through the Google Search Console the existing configuration should be replicated in the HTTPs NZ/Int site profileGoogle Search Console
eCDN Configuration PreparationIf a eCDN is used verify that they will be able to properly serve the https domain version of the site and handle SSL when the migration is doneeCDN Provider
Web Analytics Configuration PreparationMake sure that the existing Web Analytics configuration will also monitor the trafficWeb Analytics Platform
Alternate HrefMaking sure all current webstie are point to the current tag for country. Removing Duplicate website.
During Launch
HTTPS site launchPublish the validated https site version liveProduction Environment
New version Web structure validationVerify that the URL structure on the HTTPS site versionProduction Environment
New version canonicalizationEnsure that there is only one true URL for each page - www vs non-www, slash vs. without slash, etc. in the new versionProduction Environment
Web Analytics ConfigurationAnnotate the migration date in your Web Analytics platform & verify that the configuration is set to track the https Web versionWeb Analytics Platform
SSL Server Configuration ValidationVerify the SSL configuration of your Web Server.Production Environment, SSL Test
Robots.txt UpdateRefresh the robots.txt setting in the new domain with the relevant changes and ensure major bots e.g. Google, Bing etc. are not blocked from crawling site pages, JSS, CSSRobots.txt
Rankings MonitoringStart monitoring the site rankings in parallel with the https domainRank tracking software
Current top site pages & queries identificationIdentify the top pages -and related queries- attracting organic search visibility & traffic to be prioritized when validating & monitoring the site performanceGoogle Search Console & Google Analytics
Google Search Console Registration + GeolocateRegister both domains in Google Search Console. Use geo targeting option of the main search engines webmaster account and specify target country.Google Search Console
Local optimisationNew location(s) are created and submitted to appropriate local directoriesGMB, AppleMaps, Bing etc.
BacklinksStart actively getting new backlinks to new top category pages.
After Launch
Crawling validationCrawl the site to verify that the URLs are accessible by all priority search engines, linked and served without errors, erroneous noindexations & canonicalizations & redirectsProduction Environment
XML Sitemap Release & SubmissionUpload & Verify the generated XML sitemap with the NZ/Int URL versions in the https Google Search Console profileGoogle Search Console
Official external links updateUpdate official external links pointing to the site to reflect all cTLDs versions (Social Media profiles partner sites, etc.)Official Presence in External Platforms
Ads & 3rd-Party Extension ValidationVerify that any plugins like social buttons, ads & 3rd party code are correctly working in the HTTPS URLs versions along with pointing to correct geo-locations. Scan your Website to look for non-secure content with https://www.jitbit.com/sslcheck/ as well as using https://www.whynopadlock.com/Ads & Extensions Platforms
Campaigns update ExecutionImplement the relevant ads, emailing and affiliate campaigns changes to correctly refer to correct web versionCampaigns Platforms
Crawling & Indexation MonitoringMonitor the indexation, visibility & errors of all site versionsGoogle Search Console
Rankings & Traffic MonitoringMonitor new site versions traffic and rankings activityWeb Analytics & Rank tracking Platforms
Robots.txt configuration validationVerify the robots.txt setting across all domain to make sure the configuration was properly updatedRobots.txt
Local optimisationNew location(s) are created and submitted to appropriate local directoriesGMB, AppleMaps, Bing etc.
Core Vitals
Largest Content Full PaintTools
Core Web Vitals will become a ranking Factor 2021. So you have time to work on these issues below. But, as mentino at the beginning of assessment your content loads super slow cause issues with Google crawling your pages. So, I would work on these issues sooner or later.
Read what Google says
Update Google roll out this June
Largest Contentful Paint need to be at 1.5 to pass Google’s update
This is the largest contentful element painted within the viewport.
Website developers
Prioritize your issues: We recommend fixing everything labeled "Poor" first, then prioritize your work either by issues that affect the most URLs, or by issues that affect your most important URLs. URLs labeled "Needs improvement" could be improved, but are less important to fix than Poor URLs.
We recommend reading the web.dev fast loading guidelines and the Web Fundamentals performance pages on developers.google.com for theory and guidelines on improving page speed.
Test your fixes using the PageSpeed Insights testing tool (or the Chrome Lighthouse tool, if you want to use an in-browser tool).
When you think a particular issue is fixed, click Start Tracking on the issue details page in the Search Console Core Web Vitals report.
CLS
Cumulative Layout Shift - Ways to fix
Element on the page are shift when loading on Mobile
Setting width and height as absolute
Set inline CSS element
Server push - CSS
Perload style CSS
LCP
Largest Contentful Paint - Ways to fix

Remove Blocking JavaScripts “with the files”
Remove CSS “within the files”
Audit CSS and Javascript that don’t need load
Server Push
Images - Optimize - proper size