Sounds like a bad idea to me.

I would expect latency (network round trip time) to make this entire exercise worthless. Most polyfills are 1kb or less. Splitting polyfill code amongst a bunch of small subresources that are loaded from a 3rd party domain sounds like it would be a net loss to performance. Especially since your page won’t be interactive until those resources have downloaded.

Your page will almost certainly load faster if you just put those polyfills in your main js bundle. It’ll be simpler and more reliable too.