I’m going to go outside the box and the budget a little bit on this one.
The number one scooter for hill climb speed vs portability is the Unagi model one (dual motor version).
I’ve been using it to last-mile quite a bit lately. I feel comfortable chucking it in the car because it doesn’t have any sharp edges, and it’s really light. It’s also very clean looking, so it’s my #1 choice for sneaking it into places like dentist/doctor visits.
It’s also the only scooter I’ve ever done a weighted-hill-climb test with. Check out the performance at different weights (all were with a newly minted, freshly-charged dual-motor Unagi model One. I had a backpack full of weights for the heavier runs)