Proton & Gaming: There is more than one Proton, your concern may be about the compatability layer (which works quite well in fact).

Purple Proton: If you’re a Linux user, there is no official Drive Sync client yet. Calendar sharing with non-proton accounts has some shortcomings (e.g., no recurring event updates). I’m a happy user otherwise.

Not listed in the article: I like Detrumpez Vous best. It has been around for a while, and yes, it is offered in English as well.

https://play.google.com/store/apps/details?id=com.detrumpezvous.app