Spent this session getting two players actually connected in Godot, then making it look right.
Getting connected hit four bugs in a row: a wrong node path, duplicate spawner nodes causing an already in use error, a frozen client screen caused by multiplayer authority never actually replicating to clients (fixed by having each peer derive authority from the player node name), and players falling through the floor since spawn positions were randomized on the server but never synced to the client.
Making it visible closed a few more gaps: gave each player a distinct color, fixed a camera setting that was accidentally hiding both players bodies instead of just your own, and added a MultiplayerSynchronizer so position and rotation actually sync instead of the other player staying frozen at spawn.
End result: two players can host and join, see each other in different colors, and watch each other move in real time.
Lesson learned: in Godot multiplayer, only scene structure replicates automatically. Anything computed in code needs to be recalculated the same way on every peer, or explicitly synced.
Next up: proximity or radio chat.