Some mini-PC’s have room for more than one SSD. Those are more future proof. You can start with one SSD, discover what kind of stuff you run, only containers, only VM’s, or a certain mix of those. You can always add a second SSD later — when your enclosure allows it.

5 %, that many?

Take a look at Yggdrasil.

https://yggdrasil-network.github.io/

https://github.com/venthur/blag

Don’t know if Snikket pass all your requirements, but have a look:

https://snikket.org/service/