Thank you for the suggestions.
I tried the Arduino and it worked.
My main problem was Android auto not working, and it turned out there was no need for update. All I needed was enabling it using a Diag.
These are the steps I took to enable Android Auto, for anyone else trying to do this:
1 - Visit this site and make yourself a PSA-Can-Diag (Its in French, try using google translate) (thanks to vlud for creating all the necessary tools)
2 - connect the device to your car's OBD2 port and make sure your car is on (no need for ignition, just the radio unit worked for me)
3 - open the provided app and connect to your Arduino
4 - the app reads RCC's settings and gives you all the configuration you can change (BACK UP EVERY THING FIRST!!!!)
5 - find Android Auto config and turn it on
6 - save
7 - enjoy having Android Auto!
** for people actually wanting to update **
You can find you UIN on top of the main tab in the app use that with the Peugeot API to get your license key.
I hope this can help anyone trying to update or enable Android Auto. there aren't that many English resources for this let me know if anyone wants a more detailed version with steps to build the Arduino Diag or update the unit in English.