I find it to be quite stable, I haven’t had any real issues, haven’t rebooted except for version updates which isn’t too frequent (stable). No GUI built-in, there are a few projects out there and they are working on one officially, but the cli is solid. If you have ever configured juniper routers/switches it is quite similar
For me personally… I use VyOS in a VM running on a proxmox host (optiplex, SFF) with a 4-port NIC passthrough. This solves the issue of power for me, as the host has plenty of ram allowing me to run other services without needing an additional machine (although I do have one as a spare). VyOS doesn’t currently have a GUI (one is in development), however, it has been very solid for me (also based on debian, which is nice).