I got a set of LED number plate fixtures from Amazon they replace the old units, note that they are NOT OEM and are cheap knock offs. You can get the OEM versions from a newer model BMW at the parts counter if you want only OEM parts. The cars plug doesn't fit the connector so you need to use the old bulb holder and the red/black adapter cable or buy a new plug from BMW part number 61138795954 and just just swap the connector on your car for the newer style and then you dont need the silly adapter cables.
Let me know if you want me to take any pictures of the units I have installed.
Amazon link https://www.amazon.co.uk/gp/product/B093L5475X/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1