The engagement of youth is vital, and fortunately, is already happening, big time.
But there is a deeper problem here: as you observe, policy-level solutions are both necessary and inadequate, because no one likes to be told they can no longer do what they are accustomed to doing, and policymakers have already been bought out by the corporate interests they are supposed to regulate, so trying to get policymakers to act in the public interest is like swimming upstream in a strong downstream current: all we do is wear ourselves out.
Personal solutions--usually expressed as constraints on our innately self-centered impulses, are equally flawed. Even if all good-hearted people with a strong social conscience started recycling everything, buying local and organic food, contributing to worthy environmental groups, calculating their own carbon footprint, eschewing plastics, etc., their efforts would scarcely register as a blip on the radar of a pervasive consumer culture, dominated by 24/7 advertising, everywhere.
The missing link in all of this is community. In any real sense, it has almost disappeared. We use "community" these days most commonly to refer to people we don't know and will never meet, everywhere, who share our common interests or political leanings. (I even heard one pompous right-wing college graduate refer to "the property rights community" meaning those who, like them, have dedicated their lives to protecting private property at the expense of everything else.)
But REAL community refers not to common interests, but to place: those who live in the same neighborhood, despite their diverse interests and views, and therefore have a common interest in the health and resilience of the place they live--whether or not they can unglue themselves from their screens (TV, computer, cell phone) long enough to recognize this fact. Hence my own initiative--canvassing immediate neighbors (within easy walking distance) to form Garden Guilds, whose shared agenda is to grow gardens, grow community, and grow awareness. This initiative may not (probably won't) save our planet and ourselves from global catastrophe, but at least--if it goes viral--could be instrumental in creating contiguous neighborhoods who can feed themselves from their own backyards and have experience working with their neighbors and sharing ideas and skills. And like the herding instinct of Wildebeests on the African savannah, this clustering of Garden Guilds could act as a common defense against the surrounding chaos of the inevitable collapse of our civilization into tyranny, violence, and starvation. They could become the seeds of a convivial, community-based Gaian future that none of us will live to see--but that our grandchildren just might...