I managed to select which packages to compile and which not to. I chose the sonoff-classic just to try something.
I get this error now:
Compiling .pioenvs/sonoff-classic/src/sonoff.ino.cpp.o
Compiling .pioenvs/sonoff-classic/lib988/SPI/SPI.cpp.o
xtensa-lx106-elf-g++: error: sonoff/sonoff.ino.cpp: No such file or directory
xtensa-lx106-elf-g++: fatal error: no input files
compilation terminated.
Compiling .pioenvs/sonoff-classic/lib7eb/Adafruit-GFX-Library-1.2.9/Adafruit_GFX.cpp.o
Compiling .pioenvs/sonoff-classic/lib7eb/Adafruit-GFX-Library-1.2.9/Adafruit_SPITFT.cpp.o
*** [.pioenvs/sonoff-classic/src/sonoff.ino.cpp.o] Error 1
========================== [ERROR] Took 7.14 seconds ==========================
Environment sonoff-classic [ERROR]
What am I missing?