I used Krusader for years, then (after installing Ubuntu instead of Kubuntu) I discovered Double Commander (https://github.com/doublecmd/doublecmd), which is also free software, but more cross-platform (and developed using Free Pascal/Lazarus, which makes it old-fashioned in even more ways - it even used to be hosted on SourceForge, but it looks like they moved to GitHub now).

I just tried it now. Any way to get it to not show all of my docker volumes as disk drives above the panes? There's hardly any room for a file-manager below that.

Yeah, I noticed that too, but I have fewer docker volumes, so it didn't bother me as much. As far as I can see, you can only disable the "drive buttons" completely under Configuration/Options/Layout/Show drive buttons". If you should need it, there is also a "drives list button" which shows a menu containing all available "drives".