My kids love the gymnastic rings, after the PS4 it's their favourite toy. I know they play with my Kettlebells because I never seem to find them where I leave them, but I'd really prefer them not to unless I'm supervising and even then we don't approach it as training. It's just a bot of fun.
I can't see the point of putting a kid on a program of any sort because they self regulate their training naturally, they "play" for a while and then rest for a while until they are ready to go again. It's an innate form of body awareness you lose touch with whenever you follow a program of any type.
Sure they could make better improvements if they followed a program with a rigid format but I'd rather just make it a bit of fun for them so it doesn't become a chore. They get enough rigidity and structure at school and martial arts. At home I just let them be kids so they enjoy it and come back eager the next time.
They all have different attention spans too, so they generally clock off at different times during the training, that's fine too I don't want to be a drill sergeant like my dad was to me and my brothers, so when they're done I ask them do you think you've got one more in you. Sometimes they so no and walk away but more often they'll do two or three more reps, but I don't push them, I just challenge a bit like some of their friends would..
Whenever I'm training while they are home I have to wrangle for a go on the rings or parallettes, monkey see, monkey do.