I know some 3-d party ECUs support it. All closed-source and pricey - 400 to 5000 USD. Dynojet, Bazzaz,EJK and insanely pricely trijekt
R1200GS Engine Specs:
- 2 cylinder boxer
- DOHC
- per-cylinder air intakes with dedicated valves
- drive-by-wire (no mechanical valve control)
RusEFI seems to be a way to go, however, I am not sure if Frankenso board can support:
- O2 sensor per cylinder (2x O2 sensors in total)
- TPS (with Throttle-Valve servo, BMW calls it E-GAS)
- IAC (also stepper/servo controlled)

Actuators, one for each cylinder
1. Lower Spark Plug Coil
2. Upper Spark Plug Coil
3. Fuel Injector
*4. Stepper type idle air control valve
Sensors:
1. 02 Sensor
2. Oil Pressure Sensor
*3. Cam angle sensor: The BMS-K uses this to determine firing/injection sequence for the left and for the right cylinder, independently.
*4. Knock sensor: Installed into the cylinder (not in the head).
*5. Temperature sensor in the head.
*6. TPS: Three wires
*7. Revolution sensor. It is not to read DTC, (like a hall sensor)
8. Oil temperature sensor
9. Intake air temperature sensor
more pictures https://andyw-inuk.smugmug.com/Motorcycles/R1200GS-BMW-Motorcycle-Photo/R1200GS-Schematics-Diagrams/i-MdWFsbR
and a nice video about its internal structure
Any challenges or risks you see about this conversion are welcome