So the question is: Should I (and can I) claim all of the expenses for repairs/etc, on my 2021 tax forms?
Rental expenses are claimed in the tax year they are incurred. Period. End of story.
If you were renting or attempting to rent the property prior to the sale, then you have rental expenses. Once you stop renting or attempting to rent, you no longer have rental expenses.
DO NOT confuse this with property improvements, as that is it's own completely separate and unrelated beast.
if I wait until next year, I won't be filing taxes for that state
Yes you will, as any gain realized on the sale is taxable by the state.
