Proton drive is fine, their docs service is usable but could use improvement. Their secure and private file and docs sharing with other Proton users could be a great feature, if you need it.

EDIT: I just re-tried Proton docs and spreadsheets - much improved docs, and I think the spreadsheets are a new feature; looks OK but I am on mobile right now so minimal testing.

Proton, only as transition technology.