I have a raspberry pi with a cheap 5TB usb drive at my parents house that boots up once a week and pulls a backup. I use rsnapshot to create incremental updates that takes up every little space and is easy to manage. I have the drive accessible with smb should I ever need to pull a copy from there. It’s super slow but that doesn’t matter for an off-site backup and it is super cheap
Edit: I should maybe add for future readers that cheap does not mean cheap quality but cheap relative to the amount af TB you get per dollar. I use a WD shingled drive wich is quality drive but cheap and slow af. But it doesnt matter because the internet connection is the bottleneck anyway.
What’s on my USB stick you ask… A bunch of random shit I haven’t touched for 8 years so I have no idea what it is and it’s probably outdated, but I’d be damned if that usb stick is not In my keychain because “I might need it one day”