question

You can integrate any networking or multiplayer tech you need - we don't restrict you in any way. The Photon integration is specifically enabling easy authentication and webhook callbacks on Room events, to enable custom logic. We chose to partner with them as they have a solid, mature service which is used by a very large number of developers.

I do need to disentangle two concepts, though:

The first is straight-up networking, such as you'd get with any networking package.

The other is the part people don't take into consideration quite as often, and that's dealing with NAT issues. Because not all client networking devices are created equal, some peer-to-peer connections can be extremely problematic. To deal with that, you have a server out in the cloud which either does the work to create a "tunnel" for peer-to-peer messaging, or else just proxy the messages.

If you don't care about the auth/webhook integration, the latter is still the part you'll need to consider, when thinking about what package you want to use. From my own experiences as a developer, I would personally prefer a service where there's an ops team managing the servers, as I would want to focus on the gameplay, rather than wrestle with any of that.

But again, it's entirely your call. We provide our own core services, and we're pre-integrating many third-party services, but if there are others you want to use in addition or instead, there's nothing at all preventing you from doing so.