Right— I now remember some conversation surrounding a similar problem on Titan(?).
I think a drilling drone was proposed, but communications posed complicated. That is, communicating to a base rover to route to Earth. I could picture some kind of high-tensile wire on a spool connected to the digging drone. It might not be the highest speed communication, but if it at least proved reliable, that could work, no?
It would be similar to preparing a shallow mine.
After the hole is made you get to clean it up to obtain decent samples though.
Whether this would save size or mass is to be seen, a digging drone would preferably be small though very sturdy and dense to survive landslides.