I like the sentiment, but building a website that can actually function in that setting isn't a matter of mere polyfills. You need to cut out the insane bloat like React, Lottie, etc., and just write a simple website, at which point you don't really need polyfills anyway.

In other words, if you're pulling in e.g. regenerator-runtime, you're already cutting out a substantial part of the users you're describing.