@morgoth90 See the Ooznest documentation. They plug it into the E0 endstop input on a Duet 2. https://learn.ooznest.co.uk/Guide/Assembling+Your+Original+WorkBee+XYZ+Touch+Probe/61#s309
So any free IO header on the 6HC will work fine, wired as an endstop. You may need to define it as a 'Normally Open' endstop, ie with pin inverted with !.
Yes, M675 uses the same probe for all axes.
Ian