Maybe i miss some perspective here because i never had the money to ever consider a storebought nass. The convenience never sounded like it was worth being locked down to its software.

My server is “just a pc”

I got a case with external drive slots (it also needed to fit a gpu), but i suppose external drive cases also exist that can connect to a micro computer build.

The software is proxmox, which imo is amazing. Its virtualisation and backup software and performs really well and has a proper gui.

I have numerous lxc (linux container that is not a full vm) that each run their own docker with a single service. I can ssh into those from my main system or visit the terminal and other panels in the proxmox gui. Many services host a gui to my network and i could probably make it so cli is minimal but i personally am comfortable with that so…

I also run a few full vms on it, including some windows desktops.

All of these work well next to eachother and share resources. Snapshots and backups of individual systems or data can be made with ease.

If it doesn’t fit your usecases you can get the off the shelf ones i guess but for others interested here, maybe this helps.