[jm547ster]

Gravit designer, Blender and Bitwig studio would come to mind as tools for multimedia production that are as good as anything on the other platforms.

[m4rtink]

Also Krita is improving pretty much constantly to become the "Blender of drawing".

[kebman]

Great tips! Thank you! I'm more into 2D compositing for video, but I've had my eye on Blender for some time. Not sure how it stacks up against stuff like After Effects. For audio production I already use Reaper FM, but I might give Bitwig a go too. ^^

[blcArmadillo]

Not open source; however, supposedly DaVinci Resolve is supported for Linux: https://www.blackmagicdesign.com/products/davinciresolve/. For most people the free variant should be more than enough.