[jp_sc]

That doesn't make sense. AFAIK with frameworks like Rails or Django you never expose their server directly to the Internet, you put a NGINX in front of it. And NGINX talks to the backend code via UNIX sockets, so support for it in NGINX is what matters.

And sooner rather than later you are going to need a load balancer anyway.

[ClumsyPilot]

That's not really good enough, you will have http1.1 between nginx and the actual server. Many features require actual code framework level support, like server-side push, realtime streams and grpc.

[jerven]

Yes, but these features are not yet impacting SEO.