Hi Rongyos, your questions are not annoying at all!
In fact there are several other Teensy boards that could be made to work with the OP Sound Card firmware, but they would all require significant changes to the code and the physical circuit board. The 3.5/3.6 have nearly the same type of sound output as the 3.2, but they are a physically much larger and would require a complete board redesign. Also the 3.5/3.6 processors are unavailable right now the same as the 3.2, so that is no help.
The 4.0 can also produce sound, but it only outputs the sound digitally. This means that instead of the sound output going straight to an amplifier chip, it would first have to go to a digital-analog converter, and then the amplifier. So again a complete board redesign, and also changes to the firmware.
Unfortunately such a redesign is not something I have the time for. And I can't even say that if someone started on this undertaking there might not be other complications that could arise, as I have not explored in depth all the differences. Even if I had the time, I might be hesitant to take on such a project in the current environment, because who is to say that the 4.0 or other components (amplifers or who knows what) might also be affected by shortages in the near future.
I'm sorry I can't be of more help! But I hope that answers your question.