... or are we getting shafted again? :/ I check out the dev's twitter account every now and then, but I haven't heard anything about it coming here. If anyone else has more info, or if I missed something, it'd be awesome to get an answer.

This is the DLC I'm talking about, which is already out on Steam and Epic, and is different to the free update the base game received:
https://store.steampowered.com/app/1079180/Slime_Rancher_Secret_Style_Pack/

We're also still missing the platform-exclusive DLC (they made one for each platform release.. except GOG never got one), and the VR playground:
https://store.steampowered.com/app/982310/Slime_Rancher_Galactic_Bundle/
https://store.steampowered.com/app/939480/Slime_Rancher_VR_Playground/

Sorry for the double post but there was a response from the devs:

"While GOG Galaxy receives all of our free updates, our GOG builds do not currently support external DLC. We will definitely keep you in mind if we look to expand the scope of support."
https://twitter.com/monomipark/status/1142176229782515712

So GOG gets shafted, again...

Sometimes I wonder if Valve pays developers to not give equal support to GoG customers.

Epic Store got this DLC.

Well we know epic pays devs to shaft people, just look at phoenix point...

I don't think Valve can be bothered lifting a finger to do anything, tbh. Especially not something that would cost them money, rather than bring it in for free. :B

No... this attitude is entirely on the devs.

Also, I forgot to report it here, but there have been a few threads about this on their Steam forums. The dev has closed a couple of them, but has clarified their position in the most recent threads:

So basically they want us to shut up and be thankful that they even bother to release updates. Calling bs on the doesn't support dlc claim, there are plenty of multi platform games here that have dlc. So what makes the gog version so different from every other platform that dlc is impossible? It just sounds like they are relegating us to the low priority list and focusing on the "big platfroms", just like so many other publishers here.

Eyup. The best part is that it's worded in just a way that doesn't seem to be biased, but it really is. So no-one can legally go after them for this behavior. Except maybe GOG itself, but that would require there being a legally binding clause in their contracts - which probably isn't the case, given how many devs pull this off and get away with it.

And yes, as you (and several others too!) have pointed out, there are plenty of games capable of having DRM-free DLC. Even if Monomi Park's claims are true of it being impossible due to coding issues, then they're admitting to not caring enough about their paying customers on GOG to fix their coding. So either way, their behavior is... telling.

For me this is an additional reason to support GOG.
Buy here to show that the without DRM, is a more important criterion.

"our GOG builds don't support external DLC".
What makes this game different to ANY OTHER GAME that has external DLC here? Let's look at Stellaris as a prime example.

Some developers seem to have this attitude because of software piracy. A developer on another GOG title said that they refuse to release DLC's here; the reason apparently that it appears on all the Russian software piracy sites the very next day. Which is ironic since the steam version is just as easily cracked and you are more likely to see 0day releases than the GOG version.

https://www.gog.com/forum/general/gog_is_it_truly_more_difficult_for_developers_to_update_their_games_on_gog/post71
Guess what! Turns out the claims of difficulty for updates and new content is bull. They have dev tools equivalent to steam's yet some devs and pubs just choose not to use it.

what a shame. was looking forward to buying it on this platform. not gonna buy this when the devs got that kinda attitude.

I was so close to buying this after my kids have been eyeing it for a while. Decided to come to the forum and check out what people are saying. With this information I'll probably wait until there's a deep sale if I buy it.