@mitu thanks for suggestions and help

Did you try following the steps from https://retropie.org.uk/docs/Controller-Configuration/ ?

My goal is for my friend to be able to turn on his headphones and connect much like the 8bitdo is allowing me to with the controller.

Then you need to pair & trust the headphones BT first (via bluetoothctl), just like the gamepad was paired with the RetroPie Bluetooth script.

'm confused if the above lines are related to the adapter, why would it be referred to as retropie?

It's the 'local' BT adapter and the name is taken from the hostname of the system, that's why it shows as 'retropie'. Controller is also a mis-nomer, it refers to the BT local device, not the gamepad you have connected.

@mitu The price of 11.90 € / 10.46 £ seems reasonable. Order is placed and it’s on its way to me now. Thanks for the recommendation!

@jhny0 I know that this topic is quite old, and at this point, I am doing necromancy, but what model dongle did you buy? I fought one, which thechnically works with linux machines, but the range... Well lets just say a short wired controller has better range.

thank a lot for you help
problem solved

@mitu Will do. Thanks.

@Impman66 how you set up your speedlink controller? I have SL-6566-BK xeox pro analog gamepad-wireless-black, retropie detected it but when i press&hold A to set up nothing happened.. please help

OK guys, I solved this one - eventually got the gamepad to connect via usb by trying different ports. Wouldn't work with the bluetooth dongle plugged in, but did without. Then plugged the dongle in, and searched for devices - was able to pair with the plugged in snes30 control (?) and then pair the nes30 control on second attempt. Tried a reset and everything is great!

Strange that it wouldn't let the wired keyboard take me to the gui, but it's done now.

For anyone that wants to disable onboard bluetooth and use a dongle... the above config entry is good.