Yeah check the plain gameboy section. There was a discussion a while back on the matter, though it is probably hidden right now.
Between the gameboy, games that dual booted with extras on the colour (and there were a lot of those*), GBC only titles (we did once see some disable checks to have a few boot on the GB, though nothing practical came of it), supergameboy ( https://loveconquersallgam.es/post/2350461718/fuck-the-super-game-boy-introduction
), GBA perks (of which we do have a few hacks, mostly to get the GBA extras on a GB/GBC and often then also sort the palette back to the original as such things were usually designed for first gen gba screens in mind) and things like the pokemon hacks that boost GB games up to GBC it generally would make for a classification nightmare. As essentially every emulator and flash cart does it all, give or take supergameboy for some embedded or old emulators, then it would not even gain much either
*I noted most of them usually had a DX or some distinguishing name. Apparently there were a few that didn't and a few quirks with regions where Japan might have missed something, or only the colour version made it out of Japan, or some extra bonus levels got added to things. As we already trust people to read the install notes for v1.1 versions, sub regions (plenty of games have 3 or more versions in Europe with multiple languages in each, at least for the DS anyway) and whatnot then that was also deemed unlikely to be worth noting.