Hello childhood.

Is that the ass-end of a PS/2 connector?

Keyboard socket?

For 5v stuff I just use 5v arduinos. Arduino nano every. The Pico is cheaper but level shifting is such a pain in the ass. That sparkfun level shifter is almost the cost of the Pico so just yolo it and run 5v into your io pins. If it burns out, just move it to different pins.