Within the US these things are transported all the time. The baggage staff is very familiar with dealing with the batteries & such.
I don’t work with the passenger service side of things, but I don’t recall seeing people on personal power scooters or power chairs in the terminal. So odds are you’ll check the device at the ticket counter then be wheelchaired in an airport-provided chair to the gate. Which chair comes with a flunky to push it for you.
If you haven’t flown in awhile, all the chairs were replaced a few years ago with the very wide models. It’s unlikely you’re wider than that. And if you are, you’d better tell the airline how much you weigh so they can charge you for two adjacent seats.
Checking your power chair / scooter also means the TSA checkpoint has no interaction with it. It goes as checked baggage, not as a carry-on. So you never have possession of it on the secure side and it doesn’t go through carry-on screening. yes, it’ll get looked at by the same TSA folks that inspect checked baggage. But that’s a different screening process and those folks are used to seeing these various assistive devices.
Once it’s time to board, the wheelchair flunky will take you down the jetway to the aircraft door. If you can walk at all, you’ll be expected to make your way from the aircraft door to your seat & back unassisted. Workers can give you an arm for steadying your walk until you’re in the aisle and can hold onto the seats on both sides.
If you’re flat unable to walk, you’ll be loaded onto an “aisle chair” & wheeled to your seat. That’s not really compatible with severe overweightness, wherein you’d need to struggle past each row of seats due to width. But we do move hefty 300+ pounders that way every day.
Aisle chair is not really compatible with using the lav on the aircraft either. There is a portable one on board, but it’s a major production to use it.
The smartest thing you can do is call the airline(s) you intend to use, explain exactly how big you are, how able to walk, what equipment you have, and what help you need. They’ll tell you exactly what they do at each of the airports involved, and tell you about any extra charges for extra services.
You do NOT want to show up at the airport and intend to surprise everybody with your extra needs. That won’t save you money, and will waste a bunch of time you may not have before the flight leaves and definitely will greatly increase the odds of some ball being dropped somewhere along the way.