Not recommended for most people..

For the long run, it’s a risky thing to do. If you have the assets/liquidity to pay it off if you had to, that’s different.

The trade off of a low rate for a year or two for the unknown over the long run could turn out to be a huge mistake (or brilliant)

It is harder to qualify for non owner loans today. It also depends on your credit score, income & equity.

What will you do if prime goes to 10% or more ?

Having a 30 YR fixed provides security..
For some price, you could buy the rate down and have a lower long term fixed rate if you qualify.

Borrowing with short term rates for a long term horizon is just gambling.