What’s feasible, with low gearing, is a pretty low speed.
OTOH, I really have no interest in sitting and pedaling slowly up hills. I’m content to stand up and blast up our little hills on a single speed and jog up the few super steep slopes that I I can’t manage on the bike.
I ride with platform pedals and shoes I can run in, so it isn’t a big deal. Obviously that’s not an approach that most folks would prefer. YMMV.
Otto