plexus by techlore tries to crowd source if apps work on degoogled phones. However like others said GrapheneOS has the option to use sandboxes google services. I only had one app that didn’t work at all and it was very niche.

I switched from Proton to Tutanota for two main reasons.

1. I didn’t want to put all my eggs into one basket, just like you. With Tutanota I get email and calendar in one package. For VPN and online storage I use independent solutions (Mullvad, local solution via syncthing). Related to this, I don’t like paying for a bundle of programs when I only really want to use a subset.

2. Proton isn’t following through all the way. They keep adding services (password manager and captchas recently), but they don’t provide the same experience across all devices. I’m on linux and their drive doesn’t offer a client that syncs my folder with essential documents. I have to manual upload. That’s a dealbreaker for me.

I used it for the first time on my tablet. I went from LineageOS with unlocked bootloader to debloated Stock OS.

I found it well documented. It has filters to mark apps for removal. You can be conservative or more aggressive. It tells you the purpose of each package and even if it unexpectedly affects functions that shouldn’t be linked to them at all.

Having a way to reinstall Stock android is a good precaution though.