As far as I am aware we cannot flash Redpine firmware on our Frsky receivers and or any of the clones, as there is a very limited nr flight controller with SPI receivers, and if so they are often without pa/lna and diversty. so it will limit repine to some whoops etc?
For Express LRS you can flash at least the R9 system (tx module and receivers, also Ghost hardware seems to be compatible) But maybe some vendors, can provide hardware sooner or later, as it is open……
But certainly SPI approach is nice, less weight less components and simple to keep your whole system updated inc RF link to latest standards.

Thanks for your comment. Yes, ExpressLRS is indeed very interesting project. It uses modern LoRa chips, you can choose between 900MHz or 2.4GHz, but it has one drawback – it is DIY project. So not for everybody. Redpine works out of the box. It is already implemented in the Betaflight and in the multiprotocol firmware, no DIY needed.
Anyway those two beasts are from the different worlds for different tasks. They both have its own cause.

Check also out the ExpressLRS project, the guys are making tremendous efforts. It available for 868, (you can flash your R9 Gear or build it yourself) it is technically a better link and much faster than R9 and Crossfire. Also a sx1280 based 2.4ghz version is available it can currently run at 500hz update rates (faster than Ghost) and has much smaller antenna. As it is open source, community can help in evolution and support.