React Native does not use a webview to render HTML/CSS with a JS bridge. The markup in RN maps to native iOS (UIKit) and Android (View) components. And even the JS bridge is not much of a topic anymore with RN new architecture using JSI which allows to process something like 10MB frame buffers (or 1 GB of data per second) with only couple of milliseconds of overhead.

Considering that for RN there is https://rise.tools/ for SDUI which is made by people who have worked on SDUI in Meta etc prior what is the competitive edge of using LVN which does not seem to benefit from the same sort of institutional first hand experience?

Also there seems to be a need to learn at least two different DSLs to cover both native targets vs RN's one.

It has taken RN almost a decade to be considered pretty good. Heck there was a period in Facebook/Meta where RN had the status of do-not-use for in-house projects. I'm wondering how do you aim to avoid the arduous journey that RN has had with much less resources than Meta has at its disposal and to avoid common SDUI pitfalls with no SDUI specialists.