If I'd have to guess, I'd say that it's easier to put up a Steam page, because the dev/publisher has access to the tools to do it themselves, while on GOG the process is done by their staff.

That would explain why GOG pages usually come later. Don't know if this is the case, but it's the feeling I have.

Yes, that's how it looks like and conforms to everything I've read so far.

Sounds right. It is what it is. I think they'll lose out on sales this way though.

I think you're probably very close to the truth.
Apparently it only takes about 100$ for a dev to put its game on steam. And I think there's likely some time for steam to test the game (to check if it does not contain offensive material like racist stuff, child porn, etc). After that the dev has complete control over what he wants to show on the game page - including text, screenshots and even control over the message boards.
On GOG this job likely is entirely on the staff's hands. Which can severely hinder the launch process IMO.

Considering that SNEG is mostly comprised of former GOG staff I guess it's almost a given that Chasm will launch here. But maybe GOG wants to wait a bit to see if the launch goes smoothly and without game-breaking bugs.

Still I agree with other users that they should at least give a clue about a future GOG launch. Personally I'm a bit tired of seeing steam being treated as almost a synonym for "PC gaming". It makes me start to think that if the steam store went bankrupt then all the console users would immediately imagine believe PC gaming was dead.

Unfortunately not

I've asked, directly and outright asked Devs is a game is coming to GoG and got a "nothing to announce yet" only to have it get an unannounced day 1 release 2 days later.

Contracts would have been signed
QA signed off and cleared
At the time of asking the Dev knew 100% that the game was coming to GoG

But couldn't say due to a NDA

This is the most infuriating aspect of GoG

Some games get months, even years of "Hey we're coming to GoG", while others are, by GOG's command, required to be kept in secret. And there's no pattern to how and why.

The sooner a Dev/Pub can say "Hey we're coming to GoG" the better for everyone, Devs, GoG and their customers.

The whole system in incoherent and opaque, and desperately needs fixing.

If that's how GOG do things, I honestly don't see any advantage on that. Why not say right away that the game ia also coming to GOG? That will make people think that Steam will be the only store where the game will be available and make them buy it there.

Well, possibly maybe because GoG contractually isn't allowed to publically announce that game XYZ is also releasing on GoG?

For all sorts of reasons, the chief one probably still this irrational fear of DRM-free day-1 (or close to day-1) releases taking away from those precious initial sales.
And to maintain the status quo of the other DRM-ed platform (which guarantees those precious initial sales) ruling supreme.

That may have been unfounded speculation just as well and instead the situation actually could have been that the developer(s) in principle would have liked for GoG to make a public announcement about the upcoming release a.s.a.p. but got reigned in by the publisher(s), with whom GoG is making the contracts and who ultimately have the last word on what announcements get to be made on what platforms.

Exactly my thoughts as well.

Not that hard to imagine that, in order for the release on GOG to happen at all, some publishers might insist on including a contractual clause along the lines of:

GOG sp. z o.o. hereby agrees to not advertise or make any public announcements in regards to the upcoming release of [Game] on GOG.com on the GOG.com website or any social media channels/accounts associated with or run by GOG sp. z o.o.
Noncompliance or negligence in doing so will result in the release of [Game] on GOG.com being cancelled altogether.

Just look at what happened with Horizon Zero Dawn, it came out of the blue on GOG, several months late and with no advance notice. GOG would have to be insane not to publicize such a release as soon as possible, but clearly Sony didn't want it to be known at all in order to maximize earnings on Steam.

Yeah, that makes more sense.

How the conversation went with the dev, It felt very much that they wanted to say "yes its coming to GoG" but was contractually obliged not to say.

The reason I say that, is because After game was released I replied back to them thanking them for the GoG release. He then replied back jokingly listing off a number of non committal answers they have to give in these circumstances.

He never said who was the one requiring the secrecy, however he wasn't the only developer to reply back with some variation of "nothing to announce" only for there to be a GoG release very soon after.

Now I know for many publishers, they are firmly to blame for not marketing an acknowledged GoG release, but this is different.

There absolutely is some kind of NDA mechanism with some GoG releases, and given the range of devs and pubs I've seen it happen with it most logically sits with GoG themselves.

EDIT:
Trying to find the Twitter conversation, but can't remember the game or developer

Sub-forums have been added for upcoming DANGEN Entertainment games Loretta and Hunt the Night:
https://www.gog.com/forum/loretta
https://www.gog.com/forum/hunt_the_night

And turn-based RPG Circus Electrique is coming to GOG on September 6th:
https://www.dualshockers.com/turn-based-rpg-circus-electrique-launches-this-fall/

Does anyone have a clue if upcoming Farthest Frontier might come to GOG?
It looks extremely promising!

It's from Crate Entertainment, the developers and publishers of Grim Dawn (which is available on GOG).

Maybe someone has accounts on Steam/Discord/Twitter or whatever and can ask the devs?
I guess I'm not the only one who would like that new title on GOG this autumn :)

https://store.steampowered.com/app/1044720/Farthest_Frontier/