I was able to compile after setting python 2.7 as default instead of 3.9. Now I tried to flash the recovery image but it was larger than expected (error thrown by TWRP). The "boot" image generated is smaller than the latest twrp image available for download. I haven't had time to test flashing it and in the meantime I'm wondering if that's perfectly OK or if I'm missing something.Found the tutorial and compiled a new version. I'll try it and let you guys know.