Fortunately, Frisk still has the pie. It doesn't seem like Sans is willing to eat any, being too upset to realize they're there yet. But there's a clear pattern going on here. The more Greg sings his song, the more he pulls all those things off, the better Sans is getting. Already he's starting to move again, instead of that awful stillness.

So, clearly, the next step is getting more of that crap off. Quickly.

Hurting people is one thing, and no good if it's not a fair fight where they have the chance to fight back. Breaking an awful table/bed thing, with arm restraints and leg restraints and a collar around his brother's neck? That's something else entirely. The right and fair thing to do here is to break it all so Sans can move again.

Papyrus summons a swarm of bones, directing them in a barrage to smash and shatter the table near Sans' arms. He directs them closer to the restraints themselves, breaking them so they come loose.

"Sans! Can you answer us yet?"

With the fragile state Sans is in... it's too dangerous, even for the great Papyrus, to break it all in one go. He really needs to eat something, get himself healing sooner.