*Probably* losing my tenure-track position due to COVID-19 and low enrollment
What would you do?

Disclaimer: I have never been in this situation before, so I don't speak from experience. Following my advice would be risky; that said, so would any other course of action.
Act like a rat on a sinking ship.
Your university has unilaterally rescinded your contract. Go on the official interview. Ask your chair and colleagues to be references. Make every effort to find secure and permanent employment.
Tell your chair and dean that you love your university and would like to stay in the long term. (If this is true.) Bargain with them if possible, if you decide you trust them.
One option you may (or may not) have is to go on unpaid leave if you accept another job offer. Sometimes people accept a job at University B while going on unpaid leave at University A, go to B for a year, and then decide to return to University A.
If your chair and colleagues are worthy of your loyalty, then they could not expect it under these circumstances. Good luck.