The first Zool was released for the Amiga (in OCS, AGA, and CD32 flavors), Atari ST, DOS, SNES, Genesis, Game Boy, Game Gear, and Sega Master System. I have copies of the Amiga OCS, DOS, and SNES ports in my library.
The second game was released on Amiga (same versions as the first), DOS, and the Jaguar.
Problem is though is that although Zool 2 looks great on the platforms it came out on, it would've looked far too basic for the N64 and would've been met with some nasty derision for being a 16-bit game on a 64-bit platform. And IIRC the Jaguar version did get such harsh reception from some gaming magazines back in the day.
If anything, if Gremlin had N64 dev kits, they could've done a Zool 64 on the Nintendo 64 and go the whole "3D platforming" route. But they didn't, and whether that's a wise move or not remains subject to opinion.