I am not sure WebViews are the actual problem, and fairly confident it is running the entire application + gargantuan frameworks as JavaScript is.
I am currently working on something I call HTMXNative, which is what it sounds like: using HTMX in WebViews for hybrid apps.
I haven't really looked much at memory consumption, but when I've looked so far it's been very comparable to equivalent apps using native UI.
The issue with JS is that each page gets its own execution context so they don’t share any memory. I am actually curious what does the WebView do to save on RAM here?