My understanding is that the "orange-cloud" [1] is a TLS terminating reverse proxy. Multiple upstream servers share the same Cloudflare Anycast IP. A TLS connection is formed between the client and the orange-cloud, the orange-cloud then makes forwarding decisions based on SNI (HTTPS header) or Host (HTTP header), and a separate connection is formed between the orange-cloud and the upstream server.
My question is, can the orange-cloud be implemented as a "TLS passthrough reverse proxy, based on SNI" instead? For example, the orange-cloud would not terminate the TLS connection, it would form a TCP handshake between the itself and the client, extract the SNI in the TLS clientHello packet to make its forwarding decision. Is this achievable, given that multiple upstream servers share the same anycast IP, and the hostname is only available at the clientHello, to distinguish packets with ip.dest = anycast IP?