I’m having trouble to find a bluetooth dongle at least 3.0 that needs no propietary firmware. It’s easy to find dongles advertised as linux compatible or users that claim that an specific brand works fine in linux, but the problem is that many of them are using propietary firmware without their users being aware because their distributions have already installed propietary drivers or firmwares, or ask users to install them and they just do it. I use debian main repository (without non-free software) in which I failed to make work a couple of linux compatible advertised dongles because debian ask me to install a propietary firmware. So if anyone knows for certain that some brand that needs no such a software in linux I’ll apreciate your help.
I do not know of any such dongle, but I’d like to ask you a question if you don’t mind: are you looking for a dongle with open-source firmware, or would a dongle that has its (proprietary) firmware stored in some onboard memory be acceptable?
The second option wouldn’t require you to install any proprietary firmware on your computer, but you’d still rely on the proprietary firmware for the device to run. And it might also exist, unlike a dongle with FOSS firmware.
It’s mini PC that I manage to have it working only with FOSS, even the bluetooth, but it’s a dongle with Bluetooth version 1.1 and I want to upgrade but keeping the system with FOSS.