It's a vpn from the original definition before vpn meant a proxy to get around geoblocks. I use tailscale for my home servers, my routers, for servers I have in other houses all behind NAT. I have half a dozen raspberry pi print servers in two warehouses also behind NAT and they can connect to each other and I can connect to them from CGNAT

One of the many use cases, but basically yes. Other use cases: Home automation, remote backups, media servers, photo libraries, AI assistants... you name it!

I use it only as a Personal VPN - works great!