Is it possible to use Unity's high level multiplayer components without using multiplayer service?

I'm confused about it.

 

I can't give a full answer, but I was using Unet to set up a p2p game without using the multiplayer service, but then you need to sort your own matchmaking (I was just doing it by entering the other person's ip for the time being).

 

Yes, you can use it.

 

You can use the networking stuff HLAPI or LLAPI. However, you will not be able to use the matchmaker and relay service.

If you want p2p, you will need to code NAT punch through or tell your users how to open a port on their routers. Unity told somewhere that they are considering implementing NAT punch through. However, this would be against their business model with all the new services.

If you want dedicated servers, you will need to host them yourself or distribute the server binaries.

In all situations, you will need to code your own matchmaker using sockets or maybe a web REST api.