> This is a component you can use if you're building a DIY keyboard and want to make it wireless?

Pretty much so, yes. I used similar, nice!nano inspired modules (SuperMini) to build these after I purchasing for a keeb build that didn't pan out:

1. Headphone hook that automatically switches output device to headphones when you take them off.

2. Bicycle wireless shifting module to retrofit my old wired Di2 levers.

Very noob friendly and cheap to experiment with. You can even program it with Python.