I've just noticed there is a pretty cool multiplayer fps project in the Godot templates. Open your Godot launcher and click on the Templates tab. Search for FPS and click on the project with the black mannequin face. Then click download and install. It will add two projects to your Godot launcher: a server and a client. In order to run the game, you'll have to open Godot twice: once with the server project and one with the client. Just press F5 in your server project, then F5 in your client project. In the client window, press the play button.
This project is neat, and it's got some pretty nice bot ai. They run, the shoot, etc. If you want to put these bots in your game, look for the files scenes/player/bot.tscn and scripts/player/bot.gd in the server project. I'm not saying it'll be easy to add to your game, but there is lots of interesting stuff to learn from this project and it's the most complete fps I've seen in Godot yet. Also, since the license is MIT, nothing is stopping you from just copying this project and adding your own stuff.