For sharing code (even view code) between React Native and React web projects, also consider Microsoft's ReactXP project[1]. It is very actively developed and might be what you're looking for.
Have you used it? I saw it before but felt wary about having yet another layer above RN and React. I’ve been burned by taking on too many dependencies doing magical/black box things in the past...
[1] https://github.com/Microsoft/reactxp