"you would have the most awkward ugly installation that blocks your upper cabinet doors"
No, you route it through the cabinet and if you don't want it to look ugly then you build a chase around it. I usually don't since the chase takes up more room, and no one really cares as it's in the cabinet.
And yes they are designed for venting outside, that's what these are for:
https://www.homedepot.com/p/Master-Flow-3-1-4-in-x-10-in-x-7...