Talley lights are a broadcast production tool, used originally in TV studios, to let the camera operator and tallest know the camera was “live”. Video Switcher triggered Talley lights normally require the camera studio monitor or EVF deipsigned for that camer system. If you used Sony cameras, yiu had to use a Sony EFV/Studio Monitor, same for Panasonic, etc. They were not normally interchangeable. You also need the CCU control box being used.
Features like a Talley light, are EVF/Monitor specific, and the info display is generated by the EVF/monitor, not the camera. The camera only passes the display commands being generated from the switcher (or in case of a camera recording on its own, the camera’s recording video processor sends the required Talley command), and the EVF/Monitor creates the display indication or turns on the front mounted light.
So it is not unrealistic that BM has made matching EFV/Studio Monitor’s that have the normal Studio camera functions like Talley, which are part of the EVF/Monitor function. Nothing new here, if you want a EVF or studio monitor features like Talley, you need to use the accessories designed for the specific camera being used, BM Ursa/Mini requires the BM EVF or Stuido Monitor. You wanted these functions, now you need to pay to get them.
Cheers