Hi @jp-drain-sol,
Emlid LoRa can work only with Reach devices. So, if you have a second receiver from another manufacturer, you need a couple of external LoRa for both base and rover. You can use RS-232 or a USB port on Reach RS2 to connect the radio.
A feature of the LoRa protocol is that radios from different manufacturers may be incompatible. That’s why you won’t be able to use 3rd-party radios with ours. You can use either a pair of Reach’s LoRa radio or a pair of 3rd-party external radios.
Yes, you can transmit corrections to multiple receivers. There’s no limit on the number of rovers that can be connected to the same base.
I noticed that you often answer on the forum So maybe you could have met our article describing an external UHF radio integration with a Reach RS+ earlier (it should work the same for Reach RS2). I believe it can be useful.