I'd see which newspaper had a reaction to the Khashoggi's death and try to directly contact the journalists writing the articles. They're people and they may be quite happy for the ammunition provided. For example:

https://techcrunch.com/2018/10/17/silicon-valley-hoped-the-k...

Don't let scumbags have their way, if you can tip the scale in the other direction. But again, don't want to take the moral high ground and tell people what to do.

The group's behind the Panama Papers, Cum-Ex Scandals, LuxLeaks etc.

What exactly has WikiLeaks "pursued"?

Last I checked, they had people contact them and published material they liked.

Not discounting the work they do, but there's a huge difference between them and someone like The Guardian assigning reporters to investigate a story.

None. And it's not like wikileaks made a lasting and positive change anywhere so far. Plus, after "leaking" it's quite possible your life will be destroyed. Thus the utility becomes a net negative.

The Guardian is very active in that space.