I’ve used a Slimmy brand wallet for about 12 years now. Leather, holds a few cards and a few notes, low enough profile to keep in a front pocket. The only hard part of the transition is downscaling from a pocket brick, and it sounds like you’ve already done that.

My first one had a plastic window for ID - the window plastic eventually split, but the rest of the wallet was intact. Replaced it with an all leather one, can’t see why I wouldn’t still be using it in 20 years.