My banking app works just fine on GrapheneOS, and it's required no tinkering to get it working the way I want. I can't speak for smart watches unfortunately, but I'd still recommend a Pixel with GrapheneOS if you really care about privacy. If you really don't want to go with GrapheneOS, I'd still recommend Android. Apple may be marketing towards privacy friendly, but Android still has better FOSS options, which is better than blindly trusting Apple.
My banking app works just fine on GrapheneOS, and it's required no tinkering to get it working the way I want. I can't speak for smart watches unfortunately, but I'd still recommend a Pixel with GrapheneOS if you really care about privacy. If you really don't want to go with GrapheneOS, I'd still recommend Android. Apple may be marketing towards privacy friendly, but Android still has better FOSS options, which is better than blindly trusting Apple.