I'm not very familiar with how web browsers are built, but would it be possible to write a HTML / CSS renderer on iOS that utilised JavaScriptCore for code exec

I'm not very familiar with how web browsers are built, but would it be possible to write a HTML / CSS renderer on iOS that utilised JavaScriptCore for code execution? This would abide by Apple's policies given that arbitrary code is still executed through their JavaScript engine, but would give much more flexibility on the rendering side. It would be more bespoke than simply wrapping a WKWebView. Is this a feasible path for a browser like Firefox on iOS?