Renamed a bunch of player stuff to pawn stuff and implemented extensive work on getting single-address 'netplay' code working. Not sure if I've created issues with single player but in theory it should all transfer across as if the player is simply always the host.

scenes/net_test.tscn

@@ -0,0 +1,10 @@
+[gd_scene load_steps=2 format=3 uid="uid://biha5f6hrjils"]
+
+[ext_resource type="Script" uid="uid://dk2gtt380ld51" path="res://scripts/net_test.gd" id="1_x15u5"]
+
+[node name="NetTest" type="MultiplayerSpawner" groups=["level_spawner"]]
+_spawnable_scenes = PackedStringArray("uid://ti65jukt8gvs", "uid://ck4x56txf676a", "uid://by6suwmds7xq2")
+spawn_path = NodePath(".")
+script = ExtResource("1_x15u5")
+
+[connection signal="spawned" from="." to="." method="_on_level_spawned"]