You can do that with iPhone, too, using the (poorly named) "USB Camera Adapter", which splits out a USB type-A jack. (I assume you need a similar adapter on most Android phones, too, since I've never seen one with a type-A jack built in.)
reminds me the time i had an iPhone SE (1° gen) and i could play 1-3 minutes of garageband with my Korg keyboard using it and then it stopped saying my (adapter) wasn't offcial :) the official gadget in Brazil was > 10 times more expensive than the cheap copies
I don't think so. I think usb-c based phones don't need any type of active adapter.
For example, on usb-c iphones, I can plug my camera with a c-to-c cable in mass storage mode and it shows up. So I expect a dumb a-to-c adapter would work. On my lightning-based iphone, a c-to-lightning cable doesn't work.
I'd assume it's the same for androids and keyboards.