Technically you can use almost any mic that has an RJ45 and can be wired into the RR control with a PTT, audio input and ground. Not all microphones can be used (like many Icom and some Yaesu). Some may need the 3V option jumper set to add voltage to electret mic, like some Icom.
I use a modified speaker/mic I custom wired so I can use the speaker in the speaker/mic and not need to use external speaker. A friend uses the stock mic that comes with Yaesu FT857 to connect to a Kenwood TS2000, TS480, and Kenwood TM-D700.