LinuxCNC at RPI4 with using IO Pins only ?

Yes, if its a slow serial setup thing then a separate comp makes sense.
If you can setup chip parameters via SPI (like some chips I am familiar with),
hal parameters should be fine as they are not transmitted so take near 0 CPU
if not changed (and allow real time adjustments if needed)

Are you saying that some Trinamic chips can take position commands over SPI and effectively generate steps internally?

The datasheet that I just glanced at didn't seem to be saying that, for the one that I looked at.

Yes, the TMC5160 can do this and probably others
Also the ST Micro PowerStep01

Is it possible to provide a tutorial for configuring the Raspberry Pi using GPIO with LinuxCNC?

rufino wrote:

Is it possible to provide a tutorial for configuring the Raspberry Pi using GPIO with LinuxCNC?

Try  linuxcnc.org/docs/stable/html/drivers/hal_gpio.html

not is problem rpi use 3,3V and then use shift level converter module, cost 1-4 $ about and convert this gpio 3,3V to 5V out, then this 5V can connect wire to stepper motor drivers ETC, DM556.

arduino shield can use only toy motors, less than 2A motors can use, not have cnc machine motors too small, normal cnc used nema 23 470 OZ 3Nm motor 3-6Ampere current minimum cnc motors. and not need BOB card use big stepper motor drivers etc, DM556 drivers,