I do exactly what you suggest. 30mbps unlimited dtac sim costs a bit over 2k. Use it in my phone, and it connects automatically to a Gl.Inet travel router whenever I enter the room. The TV boxes, laptops, NAS, etc all connect to the travel router. You do need to keep the phone plugged in when doing this as the battery tends to drop quickly.
Torrents are fine if you use a VPN.
The travel routers currently used are GL.iNet GL-AR750S and GL-MT3000.