I think simple html+js running in a browser component or on a mobile browser remains the most popular cross platform UI on mobile. Not very fancy. But it works

I think simple html+js running in a browser component or on a mobile browser remains the most popular cross platform UI on mobile. Not very fancy. But it works pretty much everywhere and you don't need dedicated development teams for each platform or a lot of specialized development tooling. I'm currently involved in a small startup where this is the only thing we can actually afford. We don't have IO/Android developers just front end developers. We have no bandwidth to develop three UIs concurrently. Our customers don't care. Our UI is pretty slick and responsive. And we have some good designers that make us look good. I've seen several startups fail that spent way too much time obsessing over native UI/UX and ended up building the wrong product three times in parallel for three platforms at great cost as opposed to shipping something good enough much earlier and iterating on that. If users care about your app, it being native won't be the deciding factor. It's what it does; not how it does it that decides these things. People obsess about native too much when they should be focusing on functionality and design instead. Form over function is a classic design mistake.