Since one of the parent comments mentioned AJAX, I'll add that you'll also be prevented from eval'ing that payload.

Yes, I should have been more clear: CSP doesn’t allow you to download an external script and execute it, which requires unsafe-eval.

Sounds like your exception will need to become a language interpreter itself.

Does manifest v3 support wasm?

Time to package a JavaScript interpreter into wasm and run it within the extension.

You still can just write your userscript as an extension. I just checked - it works. I inserted script into HN and did some stuff.

I never said you can’t.

Can you pass data between script and extension? Implementing JS or lua should be possible.

Yes - I have done this in an MV3 extension. You can basically re-implement your own runtime and download the code and run it there instead of using eval/script tags.

It's very inefficient and it's a pain to write, but it is possible.

I suspect they will not approve extensions that do this if it becomes popular.