I’ve heard of them, but never seen one for reals.
The guys are talking about a powered paraglider - at least that is what I think it is. It would only take one, but would get them in the air.
If the want to go Part 103, there are a number of choices. There's a powered paragllider, quite often called a paramotor, which is something you wear.
In this case, your legs are the undercarriage, and they'll need to be in good shape. I just turned 60, and am in good shape, but knowing what I know from hang gliding, I would not personally fly one of these, I think my left leg would not take the stress.
Next up, there's the powered parachute, which has its own undercarriage.
This one I could do.
If you like your wings to have some bones, there are ultralight trikes that use a hang glider style wing.
I've got the itch to go try one of the light sport versions of these. If your friends decide to take up trike flying, this is what they'll be learning in.
Next up, there are the fixed wing ultralights. Here's an Aerolite 103.
There are some of these that are more airplane like, such as the Kolb Firefly.
I should add that your friends would be a bit over the design weight for the Kolb, there may be others that have a greater design weight.
Square parachutes have some interesting failure modes that limit when you can fly them. Obviously, none of these aircraft are suitable to fly in known rough air, but since they're all fly for fun only, you wouldn't knowingly do that anyway. Since you can't see what you're flying into, you need to be prepared just in case the atmosphere gets a little raucous, and for me that requires a wing with some structure.
I've heard a couple of instructors say that you should expect to do 20 hours of dual to become a safe ultralight pilot. I don't know anything about paramotor or powered parachute training. They should be simpler, all you have are the toggles and the throttle. Trikes are two axis control, and there are both two axis and three axis controlled fixed wingers.