Darktable is an excellent RAW developer. I learned it without ever knowing lightroom since I was a full-time Linux home user before I got into DSLR photography. I learned by following this playlist of tutorials and am amazed at the possibilities of creative expression in the digital darkroom.

https://www.youtube.com/playlist?list=PLsks-zRRM1ZVN_g7P6ZAs...

https://www.darktable.org/

I've been shocked how good the results I been able to get with RawTherapee are. It's extremely buggy, or was when I was last using it regularly, but it's capable of replicating or exceeding anything you can get with Lightroom except for Lightroom's profiled corrections (denoising / defringing) and the (limited) content aware editing features Lightroom has.

The distinction is basically in ease of use. What I've found is that Lightroom has a bunch of linear sliders that take you mostly through the range of what looks "good" photographically. You'll want to adjust contrast (for example) and each position of the slider will look good in its own way (though the end points obviously top out looking silly).

RawTherapee has a lot more multi-dimensional editing modes, and the vast majority of options in this multi-dimensional space make no sense at all photographically. The way Lightroom is programmed you basically get a little less control, but more expressivity, because when you change a slider the image tends to accurately reflect what you actually wanted the photograph to look like. Lightroom feels kind of magical like that, whereas you have to put in the hard work in RawTherapee. But it is quite usable, when it doesn't crash or fail to read your DNGs.

I would move from macOS to Linux as soon as there is a LR equivalent.

Darktable

Not only Darktable but Darktable paired with digiKam, :)

I looked at it. Seriously, not even close to LR.

Pretty much the case for Linux boosterism outside the command line. Almost every desktop app is a shoddy imitation of a commercial app, pushed by people who often don't know the real apps.

And if you point the shortcomings out, they whine that the shoddy app is only built by three guys and so it's unfair to judge it...