I sometimes operate a variety of different Arduino boards at the same time. These include standard Arduino, SparkFun, Adafruit, Teensy, and MiniCore.
I also observed that opening additional Arduino IDE windows permits several different sketches to be edited simultaneously, but there is only one active "boards" setting at any given time.
I will experiment with starting multiple instances of the Arduino IDE with the goal of simultaneous operation of completely different types of boards.