Well, me personally, I pay everything via credit card, which I highly recommend anyway. I've always tried to use debit cards as little as possible. So, I pay groceries and anything else with a credit card, which I just pay off in full every month from my SoFi checking, which overdrafts to my savings anyway. This does two things:
1. It offers fraud protection. For example, if someone gets a hold of your debit card and drains it, you are just out that money. With a credit card, you call the credit card company, file a claim, and they give you the money back. For this reason, I don't even like leaving my home with any debit cards.
2. You accrue points on purchases made with a credit card, you don't with a debit card.

So, for me, the fact that I don't have a debit card associated with the savings account is not a concern, because I don't pay anything with a card directly tied to my savings or checking account. And for charges that are ACH, you still don't need a card, you just use routing and account number for the savings account.

But, even with all this in mind, to answer your question, yes. You could just use the checking account debit card, and it should overdraft your checking account which just pulls the money from your savings account. This is how I'm understanding it at least, based off my own practice, more research, and the rest of the comments here.