Low Cost Raspberry Pi Contoller Board

Yes, any that has simple buffers and not optos on the outputs should work
The pinout is for this very common BOB:

www.forum.linuxcnc.org/media/kunena/atta...it-408-1000x1000.jpg

But almost any should work.


 

I don't need a lot of I/O so would the 7i96 work just as well as the 7i96S?

you have infected me, now i want a robot too

Although it doesn't have 5 step/dirs I'll mention my board here anyway. The firmware and component are loosely based on Remora SPI, and the hardware is somewhat similar to cakeslobs board:
forum.linuxcnc.org/show-your-stuff/50177-weeny-solder-bot
github.com/iforce2d/weenyPRU

The MCU is basically a 'blue pill' and unlike Remora the configuration of pins must be done in source code. It would be easy to alter the spindle PWM output to be a RC servo signal instead, assuming you don't need an actual spindle of course. But not so easy to add a 5th axis, I would need to check if any timers are still unused.

btw a 4Gb Raspberry Pi4 or Pi5 cost only 64 euro here in New Zealand, after being shipped halfway around the world. Why are they so expensive in Europe, makes no sense. As others have said, best to avoid the Pi5 for now if you want to use SPI.