Updating here with my (failed) attempt to make a working prototype, this is the early stages of having... well, "something" I guess.
Four clients successfully connected to the server (separate, 5th instance):
Next thing was to work on the sphere (which in the gamedesign is supposed to be the swarm players are suppose to hide/run away from); but I got stuck because at that time Godot didn't support properly collision with object imported from Blender; after roughly a month, I got notified on Github the thing was fixed, and I could integrate the feature I was stuck at.
When the swarm/sphere collide with object, it slow down, giving the player to run away from it: I integrated the feature... but then gave up after getting depressed and lost motivation in this project.
I can't make a multiplayer game on a single PC; going trial&error to learn the things I needed was getting a bit overhand since I had to make code additional layers of code (on top of server/client interaction) just test basic things... also randomly missing features from Godot didn't help me out into find proper impulse into going on.
I tried to see if I could find someone willing to continue the prototype while getting 100% of founding with a patreon campaign... no luck either.
Switching into different project (for now), but you can take a look at what I did so far here: