Probably incorrect - the HTTP/2 push specification is a way for a server to send files the client along with the original request - it makes no mandates about where the files must be sourced from. It doesn't even say the data needs to be static. Cloudflare already supports push - you set a special header, and the CF proxy will GET the URLs you specify and bundle them along with the original request. No technical Cloudfront or any other CDN can't do this as well.