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.)
You even see the phone screen mirrored on the monitor, complete with mouse cursor etc.
The sad thing is it is just literal copy of the phone screen. It does not have a "desktop mode".
I've used it while on holidays connected via HDMI to the TV in the hotel, with a bluetooth keyboard/mouse and it performed admirably.
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.