I'm sorry to hear of your loss.
You can transfer either of them into a new return. You just can't transfer them both into the same return, as you can't prepare the return of a deceased person with someone else.
When you pick a coupled return to transfer, it will ask if there have been any changes, including if one of them have passed away. Then it will ask which of the two you want to transfer. You can choose one first, and then later, when you start the second return, you can choose the other.
This FAQ has more information regarding preparing returns for the deceased: https://turbotax.community.intuit.ca/community/product-information/help/can-i-prepare-a-return-with-...
When importing a return for the surviving spouse and carrying forward the surviving spouses 2019 info. I understand we need to uncheck the box for the deceased spouse, but, do you still check the box (on the surviving spouses import) saying you are filing for someone who is deceased? (This is with the understanding you will do another import/carryforward for the deceased in another file).