Like the sibling comment: I also have a raspberry pi and 3.5" USB external drive with it's own power supply. I tried a 5TB 2.5" SMR HDD powering it off the ras

Like the sibling comment: I also have a raspberry pi and 3.5" USB external drive with it's own power supply. I tried a 5TB 2.5" SMR HDD powering it off the raspberry pi for a while and it worked for maybe a year and a half. Then all of a sudden starting the Sync Process for Resilio sync would cause the drive to drop out. So I upgraded to the 8TB 3.5. Resilio sync may meet or requirements but not exactly. Resilio syncs the folders between two computers, but you don't have to sync everything. Things that don't get synced get placeholders. So it's the best of both worlds. Fast for what you use because it's local, takes zero space for what you don't. Similar to Google Drives new streaming feature, but manual and not transparent. Also for the encryption you will want the "untrusted folder setup". Syncthing has a similar product, haven't played around with it though. Like the other sibling comment Tailscale is great so you don't have to fiddle with your friends router. But be careful tailscale will need to occasionally be reauthenticated. I do not recommend SMR drives for anything other than archiving. Cheap but very slow. I think it took a week to back up my 500GB MacBook.