In addition to the difficulty of implementing Node APIs, some of the Electron APIs are also hard to implement on a different browser engine. I had particular trouble with <webview> when working on Positron.
Nevertheless, I do see the value, and I applaud you for trying to realize it!
I wonder if there’s a way to build something like this as a native Node module (i.e. Node addon) that implements the BrowserWindow API, such that an app’s main entry script can be a regular Node program.
It could then be packaged for redistribution with pkg. In that case, you’d still be bundling a copy of Node with each app, but you wouldn’t be bundling a copy of the browser engine. So each app would still be at least a few megabytes, but at least it wouldn’t be many tens of megabytes.