As mentioned in previous comments, a multi-account sync like InSync (multi-account sync software, because even Google hasn't managed to implement it) would be fantastic. I use a personal Proton account and a business account, and I'd create another business account for a future project, but the deal-breaker is: I can only sync one account at a time.

Because of the low number of upvotes, I assume the botched title is the problem.

I can't understand why this feature doesn't have more votes. This was a huge issue for Dropbox for many years that they have to solve a lot of tech debt to be able to resolve. If you're attracted to privacy, you have personal and business accounts and you need to access both of these in a seamless manner.

Multi account on Proton Drive PC and Android. I cannot have my professional and personal email drives accessible without logging out and in!

Some combination of apps/platform allows for multi-account management/switching. Proton Mail does that across the board, Proton Drive does that in the browser but not on mobile, Proton Pass allows this on the desktop but not with the browser extension... Considering Proton is a suite of apps, all apps/platform should consistently allow multiple accounts switching/management regardless of the combination of apps/platform... Another similar feedback but product-based: https://protonmail.uservoice.com/forums/953584-proton-pass-authenticator/suggestions/47485043-account-switching-for-browser-extension

Multi accounts on Proton Drive PC application (like Proton Mail) would be very helpful for users who have more than 1 account to manage, we need to make loggout and login again on Drive creating every time a new folder in PC w/ different names to access the documments on the cloud. it makes everything confuse and impractical.

Additionally, I suggest to implement an access history for docs by email/PC-ID and an easy buttom to download the registers (for controllers/creators) - very useful for business access control and compliance.