You'll find a Jet Gun Workbench inside the Liberty Fall's Motel. Go to the G6 coordinates, which will be accessible upon spawn.
Be careful when you approach the doorway, as a bunch of zombies will come out of it.
Once inside, you'll find a Workbench for the Thrustodyne M23, aka the Jet Gun Wonder Weapon. However, you'll need to find its parts to begin crafting it. You must obtain the following items:
We'll break down all these locations to help you find each item for the Black Ops 6 Zombies Liberty Falls Easter Egg.
The Water Valve is located at the E4 coordinates, near the Speed Cola Perk Cola.
Approach the Water Valve and hold down the 'Interact' button, which is the same interaction as your reload. I know it's a bit confusing since there's no prompt here, but it will work if you press this button.
Grab the Water Valve and start making your way to the Liberty Lanes bowling alley. It's located at the E7 coordinates.
You should find a water gauge near the bowling lanes. Knock off the door on it by simply punching it, then place the Water Valve inside. Your goal here is to build up the water pressure by holding the interaction for it. You'll see a meter for it on the left, which you must gradually fill up. It'll be pretty challenging to fill it up if you're running it solo, especially with all the zombie hordes. I found it best to just perform this interaction toward the end of the round when it's not so hectic.
Once completed, the Water Pressure Gauge will drop, transferring over to your Quest items inventory.
After you've acquired the Water Pressure Gauge, travel over to graveyard at the coordinates B4/B5.
You must eliminate the Groundskeeper zombie, who spawns toward the end of the match. I noticed that this enemy typically appears near the top-right corner of the graveyard (next to a mausoleum).
Once you've killed the Groundskeeper, look around its body to locate the Toolshed Key. You can use it to unlock the shed at the coordinates D4.
Interact with the door to the toolshed to locate the Handbrake on the table.
Use the Interact button to rummage through wire piles inside. After a few attempts, you should find the Electrical Wires.
Now that you've acquired all three parts for the Jet Gun, go to the Motel Workbench to begin crafting it. You'll now have the power of a Wonder Weapon at your side, allowing you to suck up zombies. The Jet Gun is also a part of another Black Ops 6 Zombies Liberty Falls Easter Egg. I'm working on a piece to solve this mystery, so stay tuned for more details.