Welcome, good to hear you're happy with your purchase. From my own experience, while it's up to you whether or not you should add a keel guard, the only time you will regret NOT putting one on, is after the fact. Ask me how I know. If you're considering it, then I'd put one on, and never have to second-guess yourself.
As to the Thrust Vectors, the price you're talking about is NOT just the Thrust Vectors, it's the Thrust Vector system AND the Lateral Thruster setup for your boat. The price for the Thrust Vector system by itself is $520.
I would suggest you DON'T take your new-to-you boat out for its maiden voyage with anyone other than a helper, and dedicate time to testing out the steering and how everything works. Coming from an I/O, it will definitely be an adjustment, and you'll be better able to determine if you feel like you'll need any steering system, or if your past experience will help you quickly learn how to maneuver your boat. You'll also be kicking yourself if/when the Thrust Vectors go on sale later in the year, and you can manage your boat until they go on sale.
I've not had the lateral thrusters, but my boat is a 2019, when some improvements were made. I wish there were someone around me who had the lateral thrusters on their boat so that I could test the feel of them, but my boat wouldn't require the extra hardware that yours would, so for me, $230 isn't as big a hit, where you would be looking at $525. I can honestly say at YOUR price point, I'd be holding off on the lateral thrusters for a bit, until you get some more time behind the wheel. At my price point, this may be the year I add them to my boat.
Check out this thread from last year for an idea of the sale offer. This may or may not be offered again, but mebbe it helps your decision process:
https://jetboaters.net/threads/jetboatpilot-thrust-vector-lateral-thruster-sale-event-2023.42231/