I am sorry for your loss,
The basis of the house for the purposes of the sale is the fair market value on the date of death od the decedent (your father in January of 2022) plus the costs of the improvements made after death.
You need to establish the basis on the date of death and the IRS is only required to accept an appraisal from a certified real estate appraiser (although you may be able to slip by with a competitive market analysis from a local real estate broker).
If the estate sold the house, then the estate would be required to file Form 1041.
See https://www.irs.gov/instructions/i1041#en_US_2022_publink1000285942
