Happy* IINA user here. I use youtube keybindings + 'video speed controller' (chrome extension) keybindings for quick speed up/down/reset and skipping back/forward through videos).
* It did have a problem with crazy power consumption, but I think that's been fixed (haven't noticed the problem for a few months).
Did you have problem with hw acceleration? I noticed that 4k videos can be a little choppy if hw decoding is on, with sw decoding they are fine but battery life is horrible then.
I am glad there is an OSS player available, but I am never going to be able to remember this name.