[Android Head-Units] ScorpionSX:
I briefly went through the SimpleSoft website and I also didn't find any mention of an older Megane, but that doesn't necesarily mean that they don't support it (it's only 99% sure, lol :D) ... their website is one of few which is also pretty well translated in English, so I would try to contact them to see if they can help you somehow.

And you definitely should try to go through the factory settings on the stereo and the canbus selection there, to see which decoders should be there for your car. Even if there was a facelift after your car was produced, I would still take it as relevant model. For example, my Focus is made 2005 (2006 model year) and was facelifted in 2008 I think, but basically not much was changed internally, I can swap most of the stuff from the facelift to my car (and I did for a lot of things :D ) and they still work just fine. I assume it is more-or-less the same with other brands.

And one more note about the availability of the functions...well, I can again speak only from experience with Fords and mostly with my Focus, but here goes...it heavily depends on what features were available either without any "mods" by user, and also what was available on chinese market for that particular vehicle.

Let me explain a bit more. Again, I will use as an example my Focus.

Here in EU/UK market, you could get the Focus with an OEM navigation stereo which would show you the navigation instructions on the instrument cluster screen. But only if you have the "maxidot" cluster. If you have the smaller display, you will have them only on the radio. However, you could also have the radio station displayed on the cluster screen, but this option was almost never activated from the factory and if so, it was also mostly only on the maxidot screen. And even the navi instructions on the maxidot depend on the market I believe. And the maxidot screen for the cluster was an option to pay for, even when you got the navigation stereo - it was (almost) never standard equipment.

You can activate almost all of it with an ELM327 cable and a software for it, but you have to know about it.

In China, I don't think they even had the navigation stereo option available for the Focus, not even the maxidot display and all the stuff that can actually be activated on it.

So, in the development phase, when a chinese stereo developer sits in a "regular" Focus from their market with a computer to read the canbus communication, he is not aware of all the options that the car could have on other markets, therefore he will not "catch" all the information from the car, and won't implement it for the controls.

That is unless the development is being done on order by some company (much like Dynavin for example), where they provide all the available details to the developer first, and they also work with the car from the market that they target.

Of course this doesn't mean that when a car is not sold on the chinese market it will not have any support for this, it will, but I assume it's much smaller coverage than if they would sell it in China.

Hope this makes some sense. Maybe it's not entirely accurate, but it's what I was able to observe during the time that I'm interested in the topic of this aftermarket integration (since about 2014).