Are they allowed to play games at other kid's houses? Like, if they're at their friend's house and everyone is playing Super Smash Bros together, but they haven't "graduated" out of the board game phase, will they get in trouble for joining in?
In theory I like your idea, but there are so many "edge cases" that make it a challenging thing to implement, and something that could backfire if its too strict.
This is how we handle it as well. We were at friends' last night and the older kids had the N64 out. The older kids reported that ours just wanted to be read to the whole time, but early doses of things we intend to introduce anyway (video games predating modern addictive mechanics) are fine at that frequency.
We are mindful of potential Pandora's boxes though. You can't ban everything unhealthy without causing long term issues. You strive though to only introduce things when they're developmentally ready to cope with it, even if that means restrictions on yourself as an adult.
You work to constantly provide good examples via your own life, compelling narratives, etc. of people who exemplify the virtues you want to instill. That's how you help shape (the best you can) the life of someone with an innate identity to, when necessary, "just say no", or simply be uninterested in and unswayed by things that don't conform to their value system.
They aren't stifled by rules and wrestling with temptation--not valuing YT Kids is just who they are.
Good question. Yes they can play. The main absolute no-go activity with friends is something with exploration on the internet. That includes things like YT kids. But, hey you want to play Smash Bros even though we don’t at home, sure have fun!
These are not hard and fast rules, more of a system. Our youngest plays video games much younger than our oldest kid, since we have video games in the house now and didn’t with your first. However, I still make sure my youngest is getting plenty of tactile/analog play in as the majority of time spent.