I have had great success with a bluetooth dongle I ordered from Amazon. It is, of course, not FOSS. It is completely plug-and-play however, and leaves nothing on your computer. I discuss it in this Bluetooth Keyboard thread, and include a link to the product there. Results may very, but I have been pleased with mine so far. I don’t use it every day, though, so can’t vouch for its durability or anything.