I am considering get Plitch and have checked several games I have from GOG for working with Plitch.

The GOG logo is shown for Dying Light and Necromunda Hired Gun on their support pages.

There is no GOG logo for Mortal Shell and Shadow Warrior 3 on their support pages.

Does this mean that, even though Plitch works Shadow Warrior 3 from Steam, Plitch will not work with
Shadow Warrior 3 from GOG?

Thank you.

I would assume that's rather a question for the guys behind Plitch.

In general (and without knowing it for sure, of course), I would say: if the "Supported Platforms" don't mention GOG explicitly, the codes probably won't work with the GOG version of the game(s).

But again: that's a question you best ask the Plitch guys.

And since the guys behind Plitch don't seem too keen to have their customers get in contact with them (quote: "I need support - Can I write you an email? - No. Due to the number of users, we are simply not able to answer individual e-mails" - classy move), maybe ask your question on their forum: https://www.plitch.com/en/forum