> Have you tried Scala.js by any chance?

Scala.js is amazing, but it lacks lazy loading mechanism popular in TypeScript/JavaScript ecosystem -- basically you can't create a set of "tiny" modules (since the Scala compiler + standard lib are integral to each exported module), so you wind up creating a single "app.js" that contains the world (or perhaps 2 modules, one for the frontend and another for the backend).

It works but it's not ideal -- would be amazing to be able to mixin a standalone scala compiler + standard lib module that lazy loaded modules could depend on.