In summary
You need a PC to register your GP32
You need a PC to register to buy Commercial games
An SMC reader for your Mac, At the moment.
If you have 10.1x on your Mac you can use Mr SPIVs MacLink software, without a firmware patch
If you have 10.2x on your Mac you can use Mr SPIVs MacLink software, with a firmware patch
You may still need a PC to rip movies so that you can use them on your GP32, I keep trying, but fail.
SMC cards need to me formatted in the GP32, with MacLink
NB MacLink is NOT the OLD file conversion software, it's a command line app by Mr Spiv.
That's about it!
(B+W G3/450) + GP32