I'm actually swapping from longhorn to rook and ceph right now. Longhorn has given a lot of troubles and it does not like replica of 1 at all. Sounds like you do want a NAS, though high availability is probably over kill for home use, having a NAS makes you have that as a single point of failure. I ended up upgrading all my nodes and keeping replication off 3 since I still wanted the high availability.
I would guess it doesn’t like replica at 1 indeed.
And using a NAS would be a single point of failure indeed, but how I’m using Longhorn right now already is (my storage node goes down, my cluster would be unstable)