My kiddo has easily spent 500+ on Roblox across birthday/Xmas gift cards/chores. I can't stand that almost all of the games seem to have a pay to win aspect, or are heavily advertising every chance they get. As a gamer dad, I try to show my kid better games to play, but because they aren't free, his friends can't play. Just drives him to keep playing and wanting more Robux. It's compounded when his favorite Youtubers…
Buy him DRM free games on GOG. I Do this for young relatives. Ive been shown WhatsApp threads of the young teens who play the DRM-free games i upload - my google drive ID is effectively referenced as some kind of deity lol Side benefit: No online play or interaction with the outside world, only with your own group (usually)
I personally got a Miyoo for my kid but ended up getting one for myself. The fun and nostalgia are there.