What storage does "Cloudflare Pages" use internally for static assets? I'm asking because we are using "Workers for Platforms," and currently, we use R2 for static assets. Would moving static assets from R2 to "Cloudflare Pages" potentially result in significant performance gains worldwide?

Maybe a little bit. Pages runs on KV, which in some cases might be faster. The main selling point with Pages is that you don't pay for asset requests.