I just installed an xtrons android head (designed in uk) unit in my e46. They also make them for your e39 and they are designed specifically for our cars. Installed backup cam, wireless car play and I love it. I think I’m 400 all in. Here’s a quick search of one for yours. All plug and play.
https://www.ebay.com/itm/Android-10-....m46890.l49292