I've been working on an server myself, and have login through character creation working. Agreed - entering the world from character selection is basically the choke point. SO much to get working/figure out beforehand. I'm working through this myself at the moment. Feels like once I crack this nut, the rest of the game will be a lot easier to deal with (modulo all the server side-only assets.)
I'm doing the REP server as well as emulated HUBs all written in a single go service, just to get things working. Ideally I'll have claude code figure out the proper branch point from vanilla lumberyard and have it spit out C++ for all the NW-specific code that isn't in the LY source. Operating under the assumption that the hub servers are C++ running the same code as the client, but in headless mode (so same physics engine, etc.)
Please reach out if you've made it beyond spawning the player/loading the level (state 14). would love to see what I've missed.