I use the Teensy solution since two or three years now .
Since the Pixracers boards have a Frsky port I found interesting to have telemetry data without additional hardware, I use it a couple of times and worked well.
I also use Luaplane a version of Luapilot dedicated to planes with TTL RS232 converter .
Passtrough telemetry have more data compared to Frsky native , I hope that a free software solution will be available next.
I did not know ScottFlys telemetry, thanks for the suggestion Jagger