Bit of a summary, for those who might be interested in doing a similar mod.
First of all, You will need a FL radio. Ideally a SWING radio as it has a bluetooth connectivity - BLUES - doesn't so choose carefully. Once You have it, NEW 52-pin quadlock connector will be required. Available on Ali. The best is to look for DIY kit rather than adapter, as some ready made adapters DO NOT WORK! And there is a VERY limited space behind factory radios! You have been warned
re-wire Your existing connector, see the above diagram (to make it clearer I have removed unecessary items), plug it in and... the most complicated part - try to find somebody to disable Component Protection for You. I have visited 7. yes SEVEN, so called independent specialists around my area and they all were unable to do so. Neverthless, if You did your wiring right, Your radio will work - just some features wont be accessible/available until you will find THE right guy to assist You with CP removal. I went step ahead, and I purchased FL speedometer from the same vehicle I got radio from (NOT a maxidot) which allegedly may help with CP removal.
For complete integration of Your NEW FL radio unit, You will also require a in-Car microphone 🤔 Ive tried couple of aftermarket in-car microphones, but they would not work with the previously trialed Android Head Unit nor with genuine radio, so Ive decided to go full OEM by purchasing 3BD035711 - it worked like a charm.
Once You got Your radio sorted You may consider adding VAG OEM Smartphone holder with USB as the PID/Garmin/Navigon unit no longer works with Your new radio 😛
Below list will ONLY work with those vehicles which had PID installed previously, as apparently, there is an additional metal bracket inside the dash which vehicles without PID simply dont have. If you have a cut out in Your dash for PID/Smartphone holder with blanking clip-on insert - You are OK. If there is NOT - this retrofit wont be available for Your car - at least not that easily.
so, once You replaced Your radio, and removed Component Protection, and You want to replace Your NOT WORKING PID wih Smartphone Holder with USB port, You will need following:
(1) 1S0035935 B - base plate for the FL Smartphone Holder (see notes below),
(2) 5Q0035726N - USB connector,
(3) N10592102 - 2x M4 x14 crews (if You had a PID installed before use the old screws),
(4) 5G0035222 - USB & AUX wiring harness (IMPORTANT: see notes in the text below),
(5) 1ST051435B - complete Smartphine holder as a kit or available as two separate items:
A. 1S0035936D - bottom part for the Mobile Holder,
B. 1S0051435D - Upper Part for the Mobile Holder,
(6*) 1S0 035 491 - blanking plate - optional.
NOTES:
(1) If You are lucky, You may be able to find baseplate already with USB connector. A lot of breakers they sell it as ONE part. Be VERY vigilant as some breakers/dismantlers may try to sell a PID baseplate under this part number, look closely at the photos and read the description!!
(3) it doesnt have to be OEM screw, as long bolt's head fits in to the recess on the base plate - You will be fine.
(5) avoid cheap copies from ali or ebay!! USB cable needs to look like a coaxial cable NOT like normal wire - see photo. Otherwise, it may not work at least it would NOT work in my case and Ive tried at least two different ones. If You will decide to use only USB part of the wiring loom, Black plug is not needed as this is for Your additional AUX port. therefore - 4-wires from the green 12-pin connector can be removed. Green 12-pin connector will be ONLY used to provide additional voltage to the USB port.
This part of the write up is for those, whos vehicles were not fitted with PID's and where internal bracket nor cut-out may not be present.
As the supplied wiring loom is very long, it is possible to add USB port as well additional AUX port next to Your cigarette lighter down at Your center console using 1S0863617B (NOTE: part 5Q0035726N is still required), buttons can be replaced or blanked or, if Your imagination and Your DIY skills allows it, there is so much wire supplied that You could install it in Your arm rest
Some of the reference material was taken from HERE thanks to @danikd for pointing me there. The rest was by trial and error.
My MOD is still in progress, @maxychat & @RickB Ive just posted my speedo to The Guru in the Netherlands.
I shall return, once will have more to report...