Stop freaking out, you can do this. Don’t try to build a full server farm on day one. Start small, get something that actually works, then iterate.

Practical path: plug an external HDD into your Linux Mint box and install Syncthing on both the Pixel 8 and the PC. Syncthing is dead simple for backups, it syncs your phone photos to the PC with no cloud, no port forwarding, and it Just Works. Install with apt on Mint, install the Android app on the Pixel, share the camera/DCIM folder, accept the device link. You’ll have automatic backups within an hour and you’ll actually learn how files move around.

When you’re comfortable, add a second copy or offsite backup (cheap VPS, friend’s house, or a rotating drive). If you want a web gallery, user accounts, or calendar/email too, then move to Nextcloud or a small NAS OS like OpenMediaVault or TrueNAS SCALE on a dedicated box or a Raspberry Pi. Use Docker if you want portability, and always put HTTPS and a firewall in front if you expose anything to the internet.

Bottom line, stop reading dozens of guides. Do Syncthing + external drive today, then upgrade. You’ll learn a lot faster by doing than by overplanning.