The buyer is allowed to take (actually must take) depreciation deductions in the year of the sale while the seller must report depreciation recapture income in the year of the sale.

See https://www.irs.gov/publications/p537#en_US_2020_publink1000221670

So as long as you aren't selling to a related person as defined by the IRS on an installment sale, you could depreciate the property over 27.5 years correct?

27.5 years for residential rental real estate.

the buyer is selling on the installment basis and must stop depreciating. you are purchasing on the installment basis and must depreciate. many business assets are bought and sold on the installment basis and the buyer generally doesn't get clear title until all the payments are made.  nevertheless, the buyer gets to depreciate the property.

The buyer is generally considered to have equitable ownership in the property.