No thumbs means forget about any of those - especially the Sigs, with their high-effort slides.
Uh, first I’ve ever heard anyone say that SIGs have high-effort slides. I mean, they surely aren’t any more high-effort than any other top tier semi-auto (H&K, Glock, Beretta, Walther, S&W, etc).
If you truly have no thumbs, you might want to consider a double action revolver. A great choice would be the S&W 686P in a 4” barrel. 7 shots of .357 mag. It can also shoot .38 spl.