To replace everything. Mail, calendar, drive, vpn, password manager, documents etc. What are the pros and cons relative to proton? What are the mobile apps like? What assurances do you have they won’t go full proton in the future? And other questions
Tuta is a great german alternative with e-mail and calendar. For Drive there is many options but I don’t feel recommanding one now For VPN there is Mullvad, IVPN and NymVPN(beta) For Password Manager there is BitWarden or any popular KeePass clients but sync is mainly on you. For Documents there is CryptPad