I simply use Nextcloud to sync the vault directory. It has clients for both desktop and mobile and works perfectly fine. I use it to sync basically everything between my work, home, laptop, and mobile.
The only drawback is that I don’t know if Obsidian automatically reloads a file if it is changed - if not, and you leave the file open in the editor, you might accidentally overwrite the new file with old data.
Take a look at this list: https://networkupstools.org/stable-hcl.html
I use an older APC Back-UPS 500 to power my homelab and all network devices. So far it’s saved me from 3 power outages, and can last about 30 minutes with a 50W power draw. It doesn’t have data connections of its own (newer devices do), so I had to improvise with an ESP32 board that reports if it detects a voltage on the beeper, plus some cron jobs on Proxmox.