Well, just an update if anyone is curious.
We drained the oil, and it looked almost brand new. It was a light honey colour. in the past when doing oil changes I expect oil to be black. So we wondered if the oil was changed right before it stopped being used. We changed the filter and put new oil in. The battery was disconnected and when we connected it the radio came on but there wasn't enough juice to start the engine. The tires were only at 18 psi so we filled those to specification. Then a quick jump start and it fired up right away and seemed to run well. No warning lights on the dash or anything. Brakes seem perfectly fine. If the tires have a flat spot, I don't notice it on the road. We drove it around the block a few times and let it run for about an hour.
All seems good! Yay.