The term I like to associate with serverless is all peer-to-peer, not client-server architecture, for example any datwebsite, on datproject, and any zsite on zeronet.
There you dont have a server, really, a zite is a peer in a torrent swarm like any other, and can be found like any other torrent by its infohash (sha1) in the DHT, and can at any time go offline, while the swarm continues as nothing happened, new people can still access the zite from peers - and the zite despite rendering in a web-browser, can/should not really talk to any server, only to a peer-to-peer network. There is no "form submit" allowed on a zite, then it defeats the purpose of zeronet and similar techniques.
Another example is gun.js