i am using Ubuntu Budgie 20.10 and having problem to connect Bluetooth earphone(oneplus wireless bullets z)
I can only assume oneplus have not submitted compatibility with their hardware with the linux kernel.
It says “Plug in a dongle to use bluetooth” … so have you done this?
Sounds like you need to add a USB bluetooth device first assuming that your desktop/laptop doesnt have a compatible bluetooth device itself.
before ubuntu budgie i used Windows it works fine on that (Laptop: Hp pavilion 15 n004tx)
From a quick google search it appears that this is probably a realtek bluetooth device.
Realtek (the company) linux compatibility is pretty poor - not sure why they don’t maintain their stuff in the linux kernel…
That link may give you some pointers how to diagnose what specific device you are using.