I have joint problems in my thumbs and have trouble with thumb-heavy layouts, but have found the Sofle V2 to work well for me. For my hands it is important that the center thumb key be directly below the N and B keys, which the Sofle provides.

Details at https://josef-adamcik.cz/electronics/another_year_for_sofle....

Mitosis is the layout that I like, it doesn't require a huge thumb stretch.