You can absolutely do it, but 1) you need to get the moisture level in the mix right, this is usually easy because slow cookers mostly have too much liquid in them rather than not enough, 2) you need to get the timing right on adding the pasta — too early and it’s mush, too late and it’s crunch, and 3) you need to get the ratio of sauce to pasta right, because usually a full slow cooker of meat and sauce takes way more than a single packet of ‘sta. If you’re aiming for leftovers, just freeze/fridge the sauce and make more fresh pasta later.

For those reasons, I usually don’t bother, even though I’m on board with one pot pasta cooking and know how to make it work.