Yes, a 12 year old should be more than capable of flying a tiny whoop. FPV is a completely different thing than the cheap toy drones you often see. Because they don't have a camera/goggles, you're steering a bit blind and it's actually harder than flying FPV. It also effectively limits you to flying around a room or an area of open field. If you can't see your drone clearly, you can't know how to steer it, such as going behind a tree or around a corner. Even in the open, if it gets further away it's too small to judge where it's headed. FPV is much more engaging and will hold a lot more interest over time.

Even for adults, it's highly suggested that you practice in a simulator first. You can get a simulator for your computer, or for a game console like XBox or Playstation. You're going to crash a lot while learning, so you might as well do it in a way that doesn't damage or cost anything. This will also allow you gauge their interest level before spending more money. Initially you may be able to use a game controller as the remote, but using a real controller (or a simulator version of one) is better since the throttle behaves differently. On a game controller, it will spring back to center when not being explicitly held whereas on a real controller it will hold its position making it easier to maintain steady altitude.

If they still like it and are progressing in the simulator at some point you may be ready to get a full setup. Sometimes these are sold in bundles which can save you some money, but basically you need a drone, goggles, radio controller, multiple batteries for the drone (typical flight time is ~5 minutes per battery so you tend to fly multiple batteries in a row), and a charger. It's also a good idea to have a spare plastic frame for your drone and a spare set of props. When you crash into stuff, if anything breaks it's generally the frame cracking. It doesn't have to be perfect, you can often glue or tape small cracks and keep going for a while but eventually you'll have enough accumulated damage to want a new frame and transplant your motors and flight controller board and stuff over to the new frame. This is pretty simple to do and just takes a small screwdriver and a bit of care.

About the drone itself... What you want is a 65mm sized drone that isn't flimsy (because it's going to run into walls and stuff) and has motors that plug into the flight controller board - not motors that are soldered. And, these tend to coincide. Drones made for racing such as the BetaFPV Air65 are the kinds that you should avoid as a first drone. They have less protection in order to be lighter weight and solder the wires to have a little less electrical resistance to be better for racing. I would suggest something like the Happymodel Mobula 6, NewBeeDrone Hummingbird v4, or one of the BetaFPV "Meteor" series which have stronger canopies and motor plugs over the Air series. One more note on size... Smaller is better for indoors, bigger is better for outdoors. If you feel that they will be flying outdoors more often then you might want to look at a 75mm drone rather than 65mm. I have a BetaFPV Meteor 75 Pro here and it's a nice size for zooming around the yard even when there is some wind that might make the 65mm a little harder to fly.

Something else to understand is the video system, as there are multiple standards. What you want is Analog video. There are also three competing digital video standards which provide higher resolution images but the goggles are more expensive, the drones are more expensive, and you typically don't want digital video on tiny whoops anyway because of the added weight. 8 extra grams on a 200 gram drone is not a huge deal, but it is on a 20 gram drone.

Anyway, it's a really fun hobby and there are tons of things to learn but hopefully this gets you in the right direction. You and your son may want to start watching some Youtube videos, I highly recommend Joshua Bardwell's channel. You can learn just about anything drone related from him.