Is it still safe to update my OS?

At the moment it looks like age verification is not yet implemented in Pop!_OS. From what I can tell, System76 may only need to comply with Colorado law which should only require self-reported age attestation if passed. The worst thing you could do for your privacy and security is remain on an outdated OS. If you’re worried, I’d go ask for clarification on exactly what is being implemented and when on the Pop!_OS Chat.

Or if you’re extremely worried about this, you’ll have to switch to a distro which explicitly claims they won’t comply with such laws. According to Lunduke’s findings none of them are endorsed by Privacy Guides. But among them EndeavourOS might be the most secure (depending on configuration) and ZorinOS would be the easiest to use.