When my kids were young I did a bit of this but my kids proved to be incredibly adept at sniffing out (and emphatically resisting) my hidden agendas. My elder two in particular had very high autonomy needs and high levels of perfectionism and anxiety. Me wanting them to do something was enough to make them not want to do it, or too aware of being observed to be willing to try.
I had to back way off and avoid even the subtlest of educational-agenda interaction. These days I can share authentic interests and enthusiasms and my kids are often receptive. If I'm sharing in the same manner and for the same reasons as I might share with my dh or with my friends or parents, my kids are cool with it. For example if I encountered something and it seemed like the sort of thing they'd just love. Or if it's something I've been mulling over and want to talk through with someone. Or if it's something I'm so genuinely intrigued by that I feel the need to share. But if I'm sharing because I think it's "good for them to be exposed to this" or whatever, they (inwardly) roll their eyes and check out.
Different kids, different approaches I guess. But I'm posting mostly to point out that even without "subversive" intentions, I think all unschooling parents do more than "leave their kids to learn what they learn." The members of unschooling families are part of each others' lives, and as such there's a lot of natural, authentic cross-pollination of interests and enthusiasms that occurs.