The stuff Zack and Cambry are doing seems like it can exist even without the YouTube channel, once it reaches a point of awareness in the community and becomes self-sustaining.

Most of the other YouTube products I see seem like they'd die quickly without a YouTube personality to prop them up. They aren't really filling gaps in the market, or doing something new, they're just slapping their name on something as a way to diversify their income sources. Some do seem to put a good amount of effort into helping with the design, or even work directly with the manufacturers, but they're entering crowded and well served spaces, where their primary differentiation is their YouTube channel. Fans are their target market, and I find it unlikely that most will grow beyond their audience. I don't see LTT becoming the next Craftsman, or MKBHD becoming the next Nike.

Zack started out with the knife, which was a play on his YouTube success, but the various wheelchair adjacent things he's made stepped it up considerably. Others could do the same. It makes sense to test the waters and make some mistakes on something small before shooting for the moon. Time will tell how it plays out for all of them.

If nothing else, having some of these examples could inspire kids to want to start businesses making stuff instead of just wanting to be YouTube famous.

There’s Hank and John Green’s https://good.store e-commerce website that sells socks, coffee, and soap and donates 100% of the profit to charity.

It’s a borderline example since they largely sell to their fans, but the products have broad appeal and are not branded with their names like most YouTuber products.

They are aiming for the “Newman’s Own” model of creating good products and then donating 100% of profit to charity.

Youtuber Mark Rober started CrunchLabs from his youtube channel.

for better or worse the entire Mr Beast empire and, to an extent, Logan Paul and his ventures (Prime, etc)

I think you mean promotion instead of distribution?