Nice writeup. Full disclosure, I work on one of the alternatives so take it with salt: for the Workspace-shaped stuff (docs, calendar, drive, chat, calls) we built uOS. It runs in the browser, end-to-end encrypted so the server literally can't read your content, hosted in Switzerland, free for personal use (alpha, invite-only for now; orgs can self-host under licence). I won't pretend it replaces your whole list today, but if the "provider can't read it" part is what you're chasing, I'm glad to get you a seat to test. Either way, respect for doing the work instead of just talking about it.

Disclosure: I work on one of these, so flag it as such. Adding uOS since the thread is about de-Google options: an all-in-one that runs in the browser (nothing to install), covering chat, calendar, files, docs, spreadsheets and calls under one account, end-to-end encrypted and hosted in Europe. Free for individuals. Not a FOSS Android app like most of the list, more a replacement for the Google Workspace layer, and it's alpha by invitation rather than install-and-go today. Putting it here so people weighing a full de-Google have it on the radar.