Hi
Could someone tell me which bluetooth (USB) can I buy for working with MT 7? I Have BCM2035B and CSR8510 A10 but it's only detected by ROS. I can't use it.

I'd say that ROS only supports BT hardware vased on chipsets akso used by hardware made by Mikrotik. I could only find references to Quectel's BG77 in this context. So I guess that if you find a BT modem, based on this chipset, it might work.

What you see is not ROS support, only generic USB enuneration and mapping from vendor ID and device ID to names, available in usb.ids file (which has nothing to do with actual device drivers).

Thanks for advice.

The bluetooth in the Mikrotik is for the IoT. And all the control is located there. Therefore, it is possible that the corresponding package is required for operation.