Any feedback would be greatly appreciated.
Nozzle:
0.4-0.8mm
Layer:
0.24-0.4 (Recommended)
No supports needed
Scale it as you like :)
You can print multi color keychain with a single nozzle (use this video for reference) or using multiple extruders, palette, etc.
Just use Cura's pause at layer tool or color change in PrusaSlicer.