Welcome here. I can relate because like you my son doesn’t drive and I seem to be his current (and consistent) ride.
My son will head out on foot on our property but because we live in a farm hasn’t tried to walk to town yet. I don’t have to worry when he is on medication but a couple of time he left at dusk unmedicated. Once, I found him on the trail, totally naked.
Another time that he disappeared late in the night, I worried, my husband was in bed and couldn’t do anything. I turned on all the light in the downstairs, and all the outside lights and eventually he walked through the door. I thought if I created a light house he would see it and get the idea to come home. That was probably a year or two ago and j had t thought about it for awhile.
Having a place of his own next door has helped in a lot of ways. It’s just close enough that we can keep an eye out. It has also kept his night voyaging at a hat for the moment. But you never know…