Sometimes while driving I look over and wonder sonderly.

Sure, all the time.

Once, my wife tells me she actually had a sort of experience of non-duality, a little epiphany one time traveling by train. As she passed by countless houses, apparently her "sonder" went off the scale and she felt kinship with all of them. Probably had something to do with the hypnotic / rhythmic passage of houses and movement of the train.

I know it may sound strange, but I’m not even convinced that anyone else is even real.

Pretty regularly. I especially get this feeling when I am people watching while driving, or just walking around and seeing a plane in the sky. When I am on a plane I always think of people down on the ground going about their day and watching some plane go by. In short, yes!

I do experience this frequently.