Naked digging challenge; don't buy the upgrade "simple clothing". It's going to take a while, but it seems achievable. I have reached the coal level so far, let's see how this goes!
Gold in a week and diamonds in two, the entire mountain is almost gone three weeks in. It would have been faster if I set my computer to run continuously, but I'll save speedrunning this for someone else.
146:09:51 and absurd time but challenge complete.