@MommaTraveler , I am sorry for your great loss.
(a) we are talking about two different things here -- 1. you and your husbands joint return for the year 2023 -- last return for the decedent. On this you prepare as MFJ and only you sign -- you tell TurboTax that your husband has passed -- it will ask for the date of demise of the decedent. This can be e-filed. You may need a copy of 2022 return so you can verify by using AGI from 2022 and of course driver's license etc.
(b) I do not believe you will have to file a form 1310 to claim any refund since you are filing jointly.
(c) The comment from my colleague @M-MTax is for the second item -- The Estate of the decedent. That part depends on the size of the Estate, whether there is a trust involved etc. and of course the State laws dictating whether you can use the simplified probate i.e. going through the whole probate process. It would be good idea to consult with your lawyer for path forward. This is where the trustee of the trust and/or the executor of the trust comes into the picture.
Please see this pub from the IRS --> About Publication 559, Survivors, Executors and Administrators | Internal Revenue Service (irs.gov)
Again my condolences -- I know it hurts ( having just lost my wife of 55 years this February ).
pk
