BP really seems capable of manifesting quite differently in different people.

It sounds like maybe your hypomania experience is mostly physiological, centered around an inability sleep/rest and then the resulting effects of that deprivation.

Whereas it also sounds like your depression can get quite severe.

I have seen/read from numerous others of BP manifesting that particular way.

Hypo/mania won't always manifest for people with a bunch of grandiosity or out-of-control spending.

Just like for some people depression can be a lot more physiological than anything else, they might not ever really feel suicidal, but they struggle to have any energy or will whatsoever to care about anything or even get out of bed and shower. It's still depression.