not quite. if OP is going to get it anyway, then he is buying a piece of hardware. the software to run is another matter. off course it would be benefitial for gOg if people buy the hardware from Valve (especially as gOg do not do hardware, so no competition) but then buy the games on gOg to run on it. in a way, if this was an easy possiblity, it would be a bit of a middle finger to Valve.

the competing service is Steam games, not the hardwares.

Steam is "literally a competing platform" it and others have support in gog galaxy.

It is indeed a beautifully priced piece of hardware and there's a metric ton of demand for them but as the time passes, there will be laptops as powerfull as the deck within the same price range or lower.
It has sold a LOT but still, Valve can't supply enough units to be disruptive. People are waiting ~1 year for a unit, I know I'm waiting since launch date and the forecasted date is October to December.

My previous post sound a bit passive-agressive wich was not my intent, however, my issue with OP is that there's nothing for GOG to support. The Deck is not a console, it's a portable pc with joysticks and people can already play GOG games on the Deck. Gog Galaxy integrates other launchers, not the other way around, why would GOG do that anyway? They already have the offline installers wich works fine with Steam.
If any "support" needs to be done in order to support the controller on the Deck, it's not GOG but Dev/Publisher responsability.

I like Linux and low end devices and if there's a thing I've learned over the years playing with both of those, is that playing games on Linux in general, require more resources to have the same level of performance as in Windows with DirectX.
Then there's the increased stutter and micro-stutter on Linux, and I'm talking about native games. The issue may be with OpenGL and not Linux in particular, since some games causes nausea to some people even in Windows (like Rogue Legacy).

I hope it will be disruptive enough to make people tweak the games instead of throwing hardware to solve problems.

Edit: Deck can be indeed very important to playing games on Linux if DRM and Anti-cheat can be made to work, since the most popular games have those (except Valves own games wich support Linux since forever) but something are tingling my small finger. I bet if those are available, will be tied to Steam or the Deck itself, not stand-alone.

I've had my Steam Deck for about a month now, and unfortunately, I haven't played a game on my PC since then. It's just so much more conveninent to play a game for 10-15 minutes, then if something comes up, I press the power button, the deck goes to sleep in 2 seconds, I come back, press the power button, the deck opens up in 2 seconds, right there in the game where I left off.

In fact, I almost missed the ending on the GOG summer sale because of it. I think I made my purchases on GOG on the very last day. I'd love to have a Galaxy app for Linux... though I think it would have to make use of the Proton Layer... I have no idea how the SteamOS works.

I am guessing it is because they don't officially support Linux, and if they did do what you suggest, it might give mixed messages about what they support and more requests for Linux versions, which clearly is low priority for them.

Not going to happen.

Another missed opportunity for the DRM-conscious store and its userbase.

Thinking about it, you are most likely right. They'd need the permission of ip holders before they can tinker with game files.

Still, while big AAA studios tend to be control freaks of the highest magnitude, it sounds like something a lot of indie devs would agree to.

Well, it's a real shame, because while Windows tend to have better support for the latest consumer stuff due its market momentum, when it comes to preservation, an open source OS like Linux with a vibrant ecosystem around it beats a proprietary OS like Windows hands down.

I'm not so sure as prices for PCs have been high for ages while all in one system should be cheaper although I haven't checked the exact prices and specs that a laptop would have at this time. As you said it's also a controller and not a basic one either so that would factor into costs too.

I was thinking of getting the deck but wanted to see how other people managed with it and to what extent the hardware was controlled or monitored by Valve and others. Anti-cheat is essentially spyware and software control at this point in time where other mechanisms can help prevent disruptive cheating.