I like both your suggestions. May I make one of my own (I'll make it regardless of anyone's approval, I'm from the USA)?
I think we should have a required age field on the sign up form (I forgot if we do have one), this data should then be used to automatically restrict users who are underage from viewing adult and mature (and maybe gory) content. They should also not have an option to disable the content restriction, but they should still be allowed to change their birthday or age field data provided they pass two consecutive CAPTCHA requests. IMO this is maybe a good way of doing it. It might violate GDPR though, so you know? Whatever floats your boat, Leaf / other Itch dev's, etc..
(I though a Leaf can float without the need for a boat... :-D j/k.)