No, I mostly focused on 8-bit home computers so far, and only ventured into other areas when I had some sort of "relationship" with those machines (like the Bombjack or Pengo arcade machines). I never owned a (classic) Gameboy, so... :)
I don't know too much about the simh project, but at least the Z80 emulator in "simh/altairz80_cpu.c" appears to use the "traditional" instruction-stepped approach with one switch-case branch per opcode: