My solution so far has been NextCloud, but I'm getting pretty fed up with it. But not enough to actually do anything about it... yet.
You could run something like Cryptomator on top of Dropbox:
It even has (paid) iOS and Android apps for mobile access.
For now I just use hetzner storage share.
My solution is… I have no fucks left to give about it. I haven’t for a long time. It works. My family will have all our photos and valuable sentimental data preserved. I keep a local backup. I spend my time on other stuff more valuable to me. If dropbox and backblaze disappear tomorrow oh well. If all my data is leaked? Knock yourself out. All the good stuff is in encrypted volumes.
My data has been breached 12 times by my count. /Twice/ by the OPM itself as I had a security clearance. DOGE goons have all our data and walked out with USB drives with all of it.
Equifax and credit agencies are a joke. My threat model is simple, nothing you can blackmail me with goes to the cloud. And that’s that. Breach me, try to hack my finances, try to steal my crypto. I have had my SIM transferred and someone unsuccessfully attacked my crypto accounts with it.
Good luck to everyone with my data :)
(25+ years in tech, ymmv)