There are old childcare cupboards that have hollows in their backs for hidden storage for books etc. Maybe check out a childcare furniture seller see what they have that can be repurposed for your needs.

Check out wire mold products. I have never worked with fiber but from what I have heard you need to watch the bend radius as it can cause issues / break. As for protecting the jack its self coming out of the plate, I am sure someone makes a cover or kit to protect that somewhere.

You would need to build it into a cabinet I’m afraid, have the ONT there, then run ethernet to where you want the router, ideally through the walls but at least if it’s not through the walls ethernet is sturdier and cheaper to replace if damaged.

Put something in front of it. It’s fiber, so it’s more fragile than other kinds of cables for yanking toddlers.

Put a cabinet or dresser or whatever in front of it. Now it’s blocked.

I’d just go ahead and buy a backup jumper right now just in case. Those jumpers are very fragile and they way they stick out of the jack means if you put a dresser or something in front of it its probably gonna break the first time something pushes it back.

Best solution is hide (by putting a bookcase or something in front of it) or relocate the cable exits the wall to be somewhere better. Otherwise just make sure that they can’t pull down the other side and that your cable is able to be bent at any radius. Those corning indestructible glass cables are great for that. The hope would be to make it so they don’t have access to where the cable is though.

Also those kid proof outlets tend to just be power outlets that help prevent crap from being pushed inside them.

They make outlet cover boxes. They go over the whole outlet with plenty of room for chords. Then use the cable housing to wherever you are going.

I think they’re called cable enclosures.