I fitted an ATOTO F7 XE Headunit.
https://m.myatoto.com/index/productDetail?productId=1585249312276316161&country=US (The UK site is out of stock)
It was largely straightforward, but the mounting of the unit in the aperture was a mission. The fitting kit I bought was no use, in the end I only used the frame from the kit and modified the existing bracket for the OEM Stereo as I was unhappy with the fit using the supplied kit.
I ran the DAB Aerial wire up the NS A Pillar as well as the Microphone wire, this has been well documented on here, and was a nice neat job thanks to the cable management in the A Pillar (Good job Fiat).
The main issue was holding the unit in the dash, a quick search online suggested that Chinese Headunits such as the ATOTO are not the same size as "proper" Double Din Units, and so there were no guarantee of fitting properly.
So, my solution was to "modify" the OEM cage and use the mounting locations from the original stereo.
By "modify" I mean hack off all the bits apart from the mounting plates that screwed into the dash.
Then, using some mounting foam pads, I trail fitted the position of the plates and offered the unit into the dash, this was a lengthy process of trail and error, but we got there. Once I was happy, I clamped the plates together with vice grip pliers and drilled holes for blots to mount it securely.
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Bolts fitted and tightened.
Thankfully nothing moved and it fitted like the OEM stereo with the 4 screws. It is really solid.
I then cut off the plastic tabs from the surround kit (as these now fouled the bracket) and fitted it and the bezel.
The bezel kit is not great, but overall it looks fine.
I hope this is useful for someone.
I expect this is slippery slope now, and I will be upgrading the speakers at some point!