Here are a few GM2 MIDI files you can look at:
Video Game Music Archive - Newly Submitted Files search -
Song Title contains "GM2"
Notes:
• The file with "(GS/GM2)" in the name is not GM2 -- it uses a Roland GS format used by the Roland SC-8850. The other files are GM2.
• The file "Another Day At Shinra HQ (GM2)" by MJG0117 sends some GM System Exclusive messages. It sends GM1 On, then GM2 On. I believe this is for fallback purposes: If a device understands the GM1 On message, but doesn't understand the GM2 On message, it might ignore the GM2 bank numbers and get almost the same GM1 instrument sounds. [Also interesting: This file sends some Roland System Exclusive messages for Roland Sound Canvas devices to display an icon ("FF7R", to represent the game name, Final Fantasy VII Remake) and text showing the title, original composer, and MIDI author ("Another Day", "at Shinra HQ", "Takafumi Imamura", "MIDI by MJG0117").]
• The files by JexuBandicoot527 often have Bank LSB missing on the channel 10 drums track (Bank MSB 120, no Bank LSB, Program Change). And they have multiple copies of Control and Program messages for some reason. And they sometimes have some tracks at the bottom with no notes but with some Program Changes with no Bank messages.
This should at least give you some idea how two other people making MIDI files make their MIDI files for GM2. You can see the correct GM2 Bank numbers are used, but maybe a GM2 System Exclusive message is omitted, in which case you are expected to already have your device in a GM2-compatible mode before you play the MIDI file.