[Searching] Bluetooth adapter with ports for audio & mic in

Hello,

I am looking for an bluetooth adapter which is capable of using a headset with its own mic and speakers and not one that uses the built in mic.
I can't find any adatper besides the fiio btr3k /5, but those are expensive and have feature specs that are more high end.
There is a board on multiple sites that has those functions but would need modding for being portable : TSA6015 / SKU: G57B532BBBD83B

Does anyone have an alternative that is "cheap"-ish? Or can you easily mod an standard adapter, so you rewire the internal mic and use a 4 pole connector for using a normal headset?

I would be happy if anyone could help. This seems so normal for me but every brand does not offer such a product and only uses built-in mics....