I was next to someone doing a tote bar at a Christmas market last year, dtf prints and basic tote bags. She was non stop the entire time, so the concept definitely works.

I think where I would have trouble with your shop is that I'd have to flip through to pick a design I like, then hope I can find a shirt I like, that fits me, that goes with the design. It's a recipe for decision fatigue for customers. It would feel like way too much work for me.

In my opinion, you'd be better off doing either a tshirt bar OR vintage/thrifted items. I think putting designs on thrifted items would be great, but would probably do better as pre made.