Hey! Yeah multiplayer can be a pain, I actually did a co-op game just recently (sync or swim on my profile) so was able to learn from that which helps a ton for a jam ahah.

IDK if I'd recommend it, did it mostly for learning and might try more services later. But I wrote a simple WebRTC signalling server in go I run on my VPS to handle lobby codes and the WebRTC handoff between the clients. Then each godot client connects to those lobbies (lobby chat and the lobby names etc are relayed through the VPS). Note: there are no godot instances running on the VPS.

Once someone launches a game, it does the WebRTC handoff to setup a full p2p connection with one player being the host. To simplify, we just made it so the driver is always the host and the cook is always the client so we don't have to worry about movement input delay (host manages simulation/movements, the client just reflects what the host sees by sending all positions at a tick rate). This is all done p2p, the VPS is out of the picture at this point, except for in the rare case a full p2p tunnel can't be made with WebRTC, to which they fall back to a TURN server I host on the VPS as well which acts as a relay.

To make it run smooth I try to interpolate positions where necessary and minimize what I am actually updating in realtime across the server. The host will always run smooth since they aren't waiting for anything on the network (the client just sends RPCs for when they should trigger certain sounds, or when they have launched the pizza). Some other little tricks are things like the pizza isn't actually physically thrown through the air, it just follows a pre-calculated arc from a raycast. So the client just receives an RPC from the host to shoot the pizza along that arc, no networking required beyond the initial call.

All that to say, every game is different! I don't have a ton of experience with other services and stuff, but you have to be careful what you are simulating on client/host side (or server side with a dedicated server). Web adds another layer of complexity to gamedev which is already hard enough!!

I'm the player 2! I also really enjoyed it, although i also struggle slightly to see the idea with the theme except for, ofc, that you have a limited time to get a good route going and deliver as many pizzas as possible. It would be awesome to see some sort of narrative that would give a reason as to why we need to deliver these pizzas fast, as well as multiple levels making structuring a good route harder every time. 
Out of curiosity, did hitting the houses give more money than just hitting the ground in front of the house?
Either way, good game!

I can add one after the jam! Just take note that compatibility between browser and desktop for the co-op feature is a bit wonky. (Just do desktop to desktop or web to web).

If you're getting lag, double check hardware acceleration is enabled on the browser. Are you having issues with the browser version?