While working on IPFS we found out that good multiplexers are hard to find. Currently we use QUIC as one of possible multiplexers. This is also good news for rust-ipfs implementation.
Yes, Akamai offers QUIC support on some CDN products. (Note: I work at Akamai)
Deps that include the CDN product Spotify uses?
My company is on Google Cloud, and by default our load balancers are set up to offer QUIC negotiation.