This determines if I will play it on GOG or Steam (I already bought it for both platforms, so I can support Piranhy Bytes as much as I can).
So will Elex have achievements and cloud saves on GOG?

Huh?

Only GOG and Piranhy bytes can tel you that.

Elex has cloud saves and ingame achievements.

Elex doesn't have GOG Galaxy achievements.

I suggest you to contact the developers and THQ Nordic to let them know your disappointment:
Piranha Bytes: info.spamblock@piranha-bytes.com
THQ Nordic contact form

The response from that email account was "not likely".

You wrote an e-mail to the Piranha Bytes and they said so?
In the past they hadn't answered me, I will have to try again even if the answer is not at all reassuring...

Elex does not have achievements on GOG, but unlike Steam, on GOG you can try different versions of the game before the updates that changed the graphics of the game in extreme and questionable ways.
You have the choice on GOG, you can chose what version you like best, unlike Steam where you are forced to play the latest patch no matter what.
Personally i think this is far more important than achievements.

The account you listed yeah. Had nothing better to do trapped at the airport.

We will see what happens. If the folks that made the port for the Neo Geo games it shouldn't be hard for them.

What happened to the graphics? Looking at the changelog, I could only find some optimization of cutscenes, bugfixes for the world map, the skills display, fixes for graphical issues to Berserker armor, mesh and texture reworks and improvements, and corrections to LOD range of red rusty metal plates.

What happened to the graphics? The only way to know is to play both versions.
And the ony way you will get the privilege to play both versions and compare will be GOG, because Steam will not offer you this option, and that was my point.

Who the hell want's achievements anyway?

They are thoroughly unnecessary and a Pain in the arse!

Anyway just in case you dont feel like switching between versions:
The nights became almost as light as the days, and because of that, a lot of nice light effects were not obvious anymore, also the moon looks washed out.
They changed dramatically the atmosphere in one of the cities.
The brightness adjustment when going indoors has been changed, making the interiors darker than before.