Beyond whether or not it's a good purchase or acquisition option, I believe that Roblox is not a viable option at all, especially if it's for your children. Simply doing a more or less in-depth search on the internet or on platforms like YouTube about Roblox reveals complaints about security issues, cases of harassment and child abuse.

If I'm not mistaken, I recently read about a class-action lawsuit being filed in the United States against Roblox, which includes parents with children who have been affected by these things.

I don't know anything about the other things you mention in the post, I'm just highlighting this about this game because, personally, a game with that bad reputation doesn't inspire any confidence in me.