It is indeed! I used to connect to a Synology NAS as remote backup location through Tailscale and the transfers would peak at around 5 MB/s.

Now I mount the NAS volumes to a host at the same location and sftp to it. It’s still dog slow at 30MB/s but that’s the NAS limitation.

Direct access to the NAS can also be achieved via Subnet Routers

https://tailscale.com/kb/1019/subnets