If you're scared of children running into material that is not appropriate for them, maybe fostering an environment where there is at least one whole trustworthy adult (preferably more, but at least one) who is open to discussing things is uh... more helpful.
You know, in the event they do meander into that thing you're afraid they'll see should you not be around.
But also so that you can discuss expectations, why you have those expectations (like actual reasons, not "because I said so"), and what to do if something they see is confusing to them or feels like it's not something they're comfortable seeing. Maybe being open about what you're worried they'll see and setting boundaries. And those boundaries should also be negotiated, especially if you're engaging with older children and teenagers.
I feel like a lot more things would be more meaningfully solved if people did this strange thing called communication and being available for it. Even if that availability takes place at a distance (voice notes and messages).