Photos auto upload to Ente Photos. I periodically manually back it up locally to my desktop and an external hard drive. I cut and paste directly from my phone to free storage and so I don't have to scroll through Ente to see where I left off last backup.

General file storage like documents I use Tresorit. Mostly because it has a Linux app, otherwise I'd probably go Proton Drive. Proton Drive I use solely for game saves and whatever other random stuff I use on my Windows partition, which is not much. Similar to photos, I have a local backup on my external hard drive for important files.

I don't back up my actual phone. I did make an app list in Notesnook, but by the time I get a new phone I tend to use the opportunity to downsize anyway. And to throw surveillance capitalism off my trail in case I made a few mistakes in not being careful over the period of owning the phone.