MEGA isn’t particularly private, no, but it has a FOSS client, doesn’t require any phone number to sign up, and provides a large amount of storage for free. While I don’t really use it, I don’t see any harm in encrypting files and then uploading them to MEGA.
Proton, on the other hand, has done some shady things, but its offerings remain some of the most private on the market and make up a decent part of many threat models including my own.