ENGINE LIGHT AND RED TRIANGLE LIGHT ON...CAR STRUGGLING TO REVERSE OUT

Put the car in neutral and see if you could push it. It would be a lot safer to have someone else push it while you were in the vehicle. It should be easily to push. Sounds like you probably have a high voltage battery problem. But no way to tell without the codes

 

In "car speak" this means, "Something's wrong. Get a code reader so we can talk and I'll tell you where to start looking."

Also, as @2010moneypit? said, it should like your brake rusted up. But that's secondary to reading the codes. We have roughly 47,670,305 threads on PC about how to read the trouble codes, so I won't repeat that info here.

 

You could try putting it quickly into R then D then back to R a few times to see if you can rock the car a little back and forwards. Is it possible the rear brake pads haven't let go of the disc due to getting wet and dried from sitting? Rocking it might encourage it to free itself.

That's a worry, look under the car and see if you still have your catalytic converter. I hope it's still there

 

Sounds like the hybrid battery has failed like thousands of others on this site.
There all dying or are going to die from sitting due to covid.

Use the search forum link up top and search the posts about the failed Gen 2 hybrid battery mine included. Search:

hybrid battery

You are about to become a G2 Hybrid Battery expert.