As an aspiring web developer, I shall refuse to use it once I learn.

I just wrote a funny script and corresponding web page:

"use strict";

(() => {
  if (navigator.getEnvironmentIntegrity !== undefined) {
    window.location.href = "https://dblsaiko.net/no-wei";
  }
})()

If this API actually becomes a thing, I might put it on all my pages.

If an internet giant like Cloudflare has already implemented and adopted this, there won’t be a lot that individual web developers can do unless this gets shot down as anti-competitive behavior (which it is). The alternative is not using CDNs and paying for servers and storage to self-host content, which will be prohibitively expensive for smaller businesses or individual hobbyists.