Thanks, that sounds promising. Which would be the general approach - trying to identify the pins used in the project and look for equivalents on an Esp32? And would I need to make available dedicated Teensy libraries for compilation on an Esp32?
In the meantime, a guy from the Teensy forum pointed me to a commit of the author that indiciates that the code originally was written for a Teensy 3.0.
I did, posting an issue on his github page, but no reply so far (nor to some older issues).
Just today I've received the IC that is part of the project; however, I'm not sure whether I have sufficient information to build it; for example I can't see in the fritzing files how the connection between the project's circuits and the radio is done (is there an M-Bus emulation? The circuit at least seems to "read" the comminication on the bus, otherwise it wouldn't be able to detect a CD with 15 five minutes songs). Also, the bluetooth modules he used are no longer available; I still have a BK8000L lying around, but again I'm not sure whether (takin into account my very limited knowledge on all this...) it would be possible to use it as a substitute with a Esp32 or a Teensy 3.2.
When I open the old fritzing file, everything seem scrambled; I'll try to re-arrange things in order to get an overview on how to proceed.