Exactly what I use. 1 TB Backblaze B2, Backrest running on my main server, my NAS, and my desktop. I should honestly probably set it up on my steam deck too for the hell of it.
Small daily backups from my servers of configs and such, bigger weekly backups from the server and the desktop.
Backing up the entire media library to a cloud service is out of the question, so I (plan to) run a manual job from each machine to an external HDD once a month, primarily as a media backup but may as well put everything there that matters, and then I shove the drive into my storage unit for a bit.
(I say “plan to” because I just got the NAS set up this past week and used this external drive for the initial media transfer, I’ve set up the jobs but haven’t run them yet)
I set this up since this reply and it’s phenomenal, what a difference compared to the old way. Thanks a ton for the rec