' Should I do a short year for the estate 5/29/20 -12/31/2020 or would it be better to elect the fiscal  year and file 5/29/2020-04/30/2021.? "

We can't really say which is better but those are the choices. I tend to go with fiscal years for estates. It gets it out of tax season. If there is K-1 income it gets pushed to the next year for the beneficiaries.