I’m new to Arduino so sorry if this is a stupid question.
How do I know if a microcontroller can be programmed using the Arduino programming language? For my project, I need a microcontroller with at least 16 programmable I/O pins, with an internal oscillator, and was thinking the ATmega32U2. Some sources say I can use the Arduino programming language, other say I can’t. Any help would be really appreciated, and even better if you could direct me to a reliable link with details on how to programme microcontrollers using my Arduino Nano Every.
The Arduino IDE can be used only with processors for which someone has written an Arduino core. There is a core for the 32U4, and that might also work with the 32U2.
I don't know of a central repository describing all the possibilities, so use your favorite search engine.
how to programme microcontrollers using my Arduino Nano Every
There is no general approach to program arbitrary microcontrollers.