SFF USB-Bluetooh Passthrough?

Hey, this is my first post, I've never used an Arduino before, but I think I may have a use for one.

I am a mechanical keyboard enthusiast, who enjoys a nice clean desk space. The only problem is, there are no decent mechanical keyboards that are wireless. I think I may be able to mod one using an Arduino Micro.

I need something small enough to fit in the keyboard case, so I need something Small Form Factor, which is why I picked the Micro, but in my initial Google search I found that the micro doesn't support something called USB host, which I assume is a subroutine or something that allows it to utilize USB input devices. My next search led to a USB host add-on for the Arduino Mini, which I assume can interface with the Micro.

My question is:
Using an Arduino Micro and some add-ons and batteries, can I make my keyboard Bluetooth, or is there a better way?

Additional info: I know how to program in several languages already and have done basic breadboarding with microcontrollers in high school, so I don't have to learn everything from scratch.

After doing more research I've discovered that I can get the keypresses directly from the keyboard controller via SPI, then send that off over Bluetooth. Again, is this the most efficient way to go about this, or is there a simpler/cheaper/smaller/better method of doing this?