It sounds like you have the motivation and persistence figured out. That’s great! Have you read Lean Startup and done some customer research? Maybe I’m wrong, but gut reaction to this app is that very few people would be willing to pay for this. If someone is privacy conscious and anti-google, Apple has a much better track record for privacy. I get multiple gigabytes of cloud backup for free and can add on additional space very cheaply, and I trust them to keep my data replicated and safe. The photo apps are also very robust and have local AI and such. It seems like a hard sell, and that the people who understand and care about end to end encryption could just set up a NextCloud instance and get E2E encrypted backups in their native photo client, in addition to office tools, general data storage, etc.

I wish you luck, and I sincerely say this to try and help you, but I think you should stop adding features and start trying to convert people to paid to see if they will.