explain that to my webgl TypeScript browser game running at 180+ FPS while rendering a large RPG tiled world with infinite procedurally JIT generated biomes, with heavy processing delegated to webworkers.

As you aren't posting code or stats I can't say much, but I'd bet a native app would still be smaller and more efficient, since you have to wrap what you're doing in an entire Chromium instance and deal with a web stack designed for documents, which is definitionally less efficient than a native alternative. Tiles aren't exactly cutting edge technology.

"Heavy processing delegated to webworkers?" That just sounds like threads but worse.