These are the important bits:

1. Use standard Settings for common Resources
   1. If the app uses Fancybox3 or auto-adds Bootstrap if necessary, adjust to use the new PageService.Activate conventions
   2. Once this is done, remove the old settings from the App-Settings
2. Use standard Settings for Image Sizes / Quality / Ratio
   1. Change all use cases which would use Default / Lightbox / Screen / Section
   2. For custom cases, create own Images-definitions in the standard settings
   3. Once this is done, remove old settings from App-Settings
   4. Use the Link.Image(...) for all image links 
   5. Add the lazy attribute loading="lazy" on all images
3. Configuration changes
   1. Resources which are meant for a specific View should be moved to View Resources
   2. Settings which are meant for a specific View should be moved to View Settings
   3. Images for Views and Content-Types should be in the App-Folder and referenced using [App:Path]/filename
   4. Try to consolidate views so they use less files and preview-images
4. Koi changes
   1. Use new standard messages pre-saved in the Koi DLL
5. UI Changes
   1. Complex content-types should be made easier to work with by implementing formulas
   2. Optimise boolean field labels
6. Razor changes
   1. Anything that used App.Resources should now use Resources (without App)
   2. Anything that used App.Settings should now use Settings (without App)
   3. Anything that used RazorBlade HtmlPage should use IPageService
   4. Anything that used Dnn request jQuery should use IPageService.Activate("jQuery")
   5. Anything that used static Koi should use ICss
7. JS Changes
   1. Drop all jQuery in all apps
   2. Use turnOn to boostrap JS
8.  Simplify
   1. In cases where we used multiple templates that just wrapped the same template, simplify to use just one template but multiple view-configurations with an Identifier or settings
9. Search Changes
   1. All search indexing should be switch to configuration or separate code file
10. Css / SASS changes
    1. Make sure it can be built without a theme by default
    2. Make sure it uses dart sass and not node-sass
    3. make sure all style-names have a app and version specific prefix like app-something7 to ensure no conflicts with existing apps
11. NPM Security: Make sure all alerts are resolved