My main project is for the Game Boy, but is it alright if I chime in?
Computers: Mac Mini (desktop), Surface Book (laptop),
MiST-based pseudo-"Amiga 3000" (since my real one bit the dust)
Keyboards:
Unicomp Ultra Classic,
Azio MK-Retro
OSes:
NixOS, AmigaOS 2.1
Editor: Emacs (Linux), CygnusEd (Amiga)
Assembler: RGBDS (GBZ80), Devpac (68k)
C++ Compiler: GCC (Linux), SAS/C (Amiga)
Music: FamiTracker + command-line converter (C++)
Graphics: Custom Amiga editor (68k assembly), though I'm thinking of switching to DeluxePaint + converter
Level Editor: Custom Amiga editor (C)
Flash Cart: Everdrive GB
Game Boy: Fat DMG, modded with ProSound + backlight
Emulator/Debugger: BGB