Imma chick. My muscle development is terrible most of the time. But I get noticeable and quick gains in climbing ability by working on bodyweight squat form, even wussy not deep enough versions. It mostly adds up to I can drive higher gears on the flats, so I have greater reserves of strength for driving low gears on hills.

That doesn't mean I quit tackling bigger hills or anything, but it does mean I progress faster... and when your cruising gear has normally been under 45 gear inches? That counts for a LOT.

It does nada for spinning ability, at least so far. So if you can't spin at all, I don't know that squats would be helpful. But that's clearly not the OP's problem .

As a teen, I mostly got by off of stair climbing (most days, I'd get in something on the order of 20-30 flights of stairs, with a 45lb backpack). That definitely also helped. By itself, it wasn't enough to get me up the 18% grade on my way home, but it meant I had some reserves to just keep slamming against it to see how far up I could get.