This forum is a bit silent but I'll try to perhaps inspire some activity. These are two supplements that I've written up for my own OW campaign. One details my take on the Ork Snakebite Clan and one on Death World regiments in the Imperial Guard.

I personally found the Snakebite Clan to be less than inspiring and so modded them to my likening by making them more primodial and drawing inspiration from the Savage Orcs in Warhammer Fantasy. One a note I should add that the encounter with these Snakebites was the first time in my campaign that the Imperial Guard experienced a major defeat, had to call it a day and withdraw from a planet permanently.

The Death World supplement is closer to what info I found in the Cathachans codices as in making them more in the Rambo-style as opposed to almost any kind of regiment. But its yet to be field tested.

Snakebite Clan

https://drive.google.com/file/d/1OxwA0IUzWswI06L3u9kP6DaQB0loPGCj/view?usp=sharing

Imperial Guard Death World Regiments

https://drive.google.com/file/d/1yL-gHcNBtKZM0GRobQzC7GE-fuXkuMPk/view?usp=sharing

If there's any issues with the links, let me know.