I built a system that does just this (it's a little bit more complex, of course, but the gist is the same) but for videos that are self-hosted (on our own bare

I built a system that does just this (it's a little bit more complex, of course, but the gist is the same) but for videos that are self-hosted (on our own bare metal servers and data storage) and automatically uploaded from devices in the field. I've never bothered to check costs because they're trivially insignificant for us; We just don't have that many users / devices. It's a niche hobby project that nets us enough money to support itself. I haven't even had to touch any of this infrastructure in literally years. My co-founder occasionally needs to plug a new data drive into the primary and/or back up storage (the server closets are on-premise in his garage) and run an interactive python script to get things configured. Otherwise it all "just works" and maintains itself perfectly well.