Right, yes, as long as the battery/power supply provides a voltage within the valid range for both the thrusters (7-20 V) and the ESCs (7-26V) it can be connected directly to the ESC power wires, and multiple ESCs can be connected in parallel.
In terms of the signal you provide, you’ll need to ensure the current draw of the thrusters (at the supply voltage) stays within the current-capacity of the supply (battery), and that the signal stays within the valid range for the ESCs. A T200 at ~15V draws ~22A at max thrust, so two of them would draw 44A. Our battery has a “Maximum continuous current draw” of 60A, and each ESC can handle a constant current of up to 30A (depending on cooling), so that shouldn’t pose any issues.
If you connect additional thrusters you’ll need to reduce the maximum signal values you send to the ESCs to avoid damaging the battery, or at least regulate the signals such that the combined current usage of all the thrusters is within what the battery can provide.
That should be fine, but you’ll need a sufficiently precise library for controlling the PWM signals: