I intend this post for established Add-on developers who want to use Angular in Google Workspace editor Add-ons and Google Apps Script webapps. This does not attempt to show how to create Add-ons or Angular apps, but the tooling and build process to use Angular apps in Add-ons. I am also assuming familiarity with installing and using CLI tools in your development workflow.
We recently had the author of this post, Spencer Easton, on an episode of Totally Unscripted to talk about this topic. This companion post provides an overview of using Angular for Add-on development. There is a cost associated with this solution has separate hosting is required for the Webpacks, but as covered by Spencer the cost is low (for a 100K+ users add-on the cost is $8/month).
Source: Modern Angular in Google Workspace Editor Add-ons
Member of Google Developers Experts Program for Google Workspace (Google Apps Script) and interested in supporting Google Workspace Devs.