My wife's just bought a 5 Door, 2013 FR which has all front and rear speakers installed, surprisingly, she's asked me to install a stereo for her, which is a first. Anyway, I've obliged, and she's got the Pioneer AppRadio 4 on order (SPH-DA120) - she didn't fancy the AVH-X8800BT that I have in my car, as she has no need for SD/CD/DVD etc. She just simply wants Radio and CarPlay.
Anyway, I've had her order;
£70 for the adapters
caraudiodirect.co.uk/ctkst01-seat-leon-2008-2014-double-din-stereo-complete-fitting-kit
£30 for the hazard light switch (needs moving)
ebay.co.uk/itm/152190728888?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
£299 -- Pioneer SPH-DA120
caraudiodirect.co.uk/head-units/apple-carplay/pioneer-sph-da120-apple-carplay-compatible-with-large-6-2-inch-capacitive-touch-screen-gps-bluetooth-android-iphone-and-mirrorlink-also-supports-appradio-mode
Regarding the Hazard switch panel, there's different part numbers with all sorts of different buttons on the Hazard panel, she actually needed 6J0927137AG. From reading around folks seem to say they're expensive. I don't find £30 out of the way, but have no idea what their RRP is. This might be an option;
ebay.co.uk/itm/Mascherine-per-autoradio-2DIN-Nero-SEAT-Ibiza-13-/271927004030?hash=item3f501ccb7e:g:eFsAAOSw~gRVoO3J
Anyway, the 3 items above - wiring harness, hazard switch and headunit - SHOULD (I hope) be enough to swap out the stock unit. I've ordered a camera (£15) and some flush fit parking sensors (£15) from Ali which I may get around to fitting at some point. I'll run the camera cable during the headunit install.
I'm just looking at speaker replacements now. The guides don't look much fun, so I may give this a miss, but it seems a shame to be put of by a bit of graft!