Can android device 'listen' for usb key input

I am trying to learn enough to make one or two android apps for myself. One in particular I want to make is that of a 'drum machine'. Yes I know these are 'wheels' that are already 'invented' However, in particular I want one to respond to a USB foot-pedal (two pedals, Start/Stop and A/B fill). I've seen on youtube a home-made USB pedal adapted from a keyboard. However this is my question. Before I invest all that time in programming, can you tell me do ANY android devices 'listen' to the usb port for devices such as a keyboard, or are they only for charging or file transfer?

I ask because it seems that none of the 'drum machine' apps on the Play Store have any 'listening' for pedals.

I'm trying to obviate the need for a drum machine on live solo gigs by incorporating an app on an android tablet that can also serve as an MP3 backing player. A repeated MP3 pattern (with the added dynamics of start stop by pedal) is often preferred to performing along to a backing track because it leaves you free to use it for many songs and gives the user more freedom in the format of the song.

Perhaps this would be a good project to include as a small course.