You can download the Debian driver here.
https://packages.debian.org/buster/all/firmware-atheros/download
Although it is proprietary, it does not cost anything to install or use. No user agreements and so on. It’s about as free as you will get. I believe this is the same driver in a Raspberry Pi. Regardless, It works just fine in the Mini as I use a Bluetooth keyboard/mouse pad with no dongle and it works great