There's no balance to be had--you must prioritize legality over privacy. You will be storing CSAM if you don't do something. You may already be storing CSAM. This is no joke. This is real and something every image hosting site deals with. You need to take it seriously. This is a "you could go to jail" concern, not a "this project might not work out" concern. The ability to store and share media privately while knowing it won't be scanned for abuse, with a free tier that doesn't even require an email address to sign up, is begging to be used for CSAM and other illegal activities. That's the sort of site you'd set up if your explicit goal was to attract CSAM. MEGA offers a similar service and they are severely burdened with abuse.
