You're not giving much info on the kind of app. Regardless, if you value your sanity, go for Flutter. It is built on the same set of principles as React, but uses a single and sound language and has superior tooling. It is also more future proof, uniquely having been adopted by both Microsoft and Canonical. With a small investment you'll also be able to run your app on the Web, the Mac and Linux, and make your own high quality animations. Flutter allows the developer to escape the sandbox all other UI toolkits provide.

Thanks, much appreciated. Apologies for my limited understanding does this mean learning Dart?

My app is a volume calculator for building materials. I'm aware of similar apps already available on the app store but they're full of advertising and not specific and over complicated for my needs. Plus I want to learn mobile dev, how better than writing my own app.

CapacitorJS and Electron are the pure HTML/CSS/JS options (myself, I combine these with React).

React Native works on Windows too, btw.

Many thanks. I shall have a look at this, seems you can migrate from Cordova too.

I hear so much bad press about electron I was hoping to avoid it, my app is so simple I can't justify the bloat. I looked at sciter for the desktop but it looks to me like I would need to work in C/C++ to embed it.