Noticed per the Fanatical sale that it is on Steam and not on GOG. Why not?

That's a question you should ask DotEmu, since they are the publishers.

However, let me throw in some thoughts of mine:

it may have something to do with the fact, that the original Little Big Adventure is on GOG already since 2011.

I don't know for sure, if the original LBA was ever on Steam (I doubt it, tbh) - but it looks like the Steam version of the Enhanced Edition and of LBA 2 got released on Steam in 2014.

Now, I believe back in 2011 DotEmu had absolutely nothing to do with LBA. It was some Didier Chanfray SARL, that bought the IP back then.

So, all the revenues made with that version went to Didier Chanfray SARL - DotEmu made zero money off of that version sold by GOG.

If DotEmu holds the rights to both LBA and LBA 2 today (and it looks that way) then they have only two possibilities to release the Enhanced Edition on GOG:

1) by giving it to owners of the original version for free - which means: zero money for DotEmu.
Almost never a move preferred by companies. Especially since the majority of GOG customers who are interested in LBA, most probably own the game already - so there is not much more money to make here.

2) by pulling the original version and selling the Enhanced Edition instead (maybe with some discount for owners of the original version) - which would enrage the GOG "community" for two reasons.

a) because pulling the original, unaltered version from the store, and
b) because demanding money from the owners of the original version (which of course, would want the Enhanced Edition, too).

So - DotEmu is best off, if they just leave things as they are.

My two cents.

I think I'll get this as I couldn't get the normalGOG version to load. Is this version more Win 7 or 10 compatible?

You mean the crappy mobile port? Yeah, no thanks.

I have not played it so I would have no idea whether it is crappy or not. I only noticed the disparity in versions.