There isn't anything particularly innovative about Duo Beyond. Inspect the Docker containers and you'll see they simply rebranded simplesamlphp and wrote a custom ngx_http_auth_request_module handler for NGINX for their authenticated reverse proxy product.

If Cisco paid 2 billion dollars for this, my mind is really blown. I'm struggling to figure out how they ended up at 2 billion because I don't see it in anything material -- perhaps the patents or a play against Okta for recurring revenue from smaller companies which might not have Cisco gear?