Hypothetical question - could a lender offer a mortgage product that alternates it’s interest rate every year? For example year 1 would be 8% interest rate, year 2 would be 0%, year 3 back to 8%, year 4 is 0%, etc.

With the new higher standard deduction and the cap on SALT, it could be worth many thousands of dollars a year to have a product like this for your mortgage. Claim the standard deduction in years when the interest rate is 0% and use itemized deductions in the years when the rate is 8%.