This is easier to do in the desktop version of TurboTax, and if you are not using the desktop version currently, you can purchase it and transfer your information into the desktop version to finish your preparation.  Essentially, you must prepare a "mock" (pretend) return as "Married Filing Separately" for the deceased taxpayer so that the PA return for your deceased spouse can be reported separately.  You are correct that PA does not allow you to file joint in this case, but the way you can file two separate state returns (when you are filing a joint Federal return), is to follow the following steps laid out in this FAQ:  https://ttlc.intuit.com/replies/3301995