If you run a legal operation, you don't have to worry about hosting company admins logging into your database. That can be done only on police inquiry.
On photos/documents, you are in a tiniest of minorities: ~99% of all smartphone users store photos in unencrypted cloud services like Google Photos and use Google Docs and MS Office 365.
(But but chats are surely the holy cow and must be encrypted - strictly demand those same users, paradoxically)
And no modern server stores passwords in plain text, and keys are not stored on servers at all.