edit: I've managed to install everything with the files on the first page.
Shades is good enough for brightness management, but of course it distorts colours. I'll have to try the other options, I've heard there's a pay app, also do some test with a calibrator. Too bad because the OLED screen is trully beautifull, that's the reasons I picked this model.
OK so the dimmer.aspp is very good. Actually a solution for me. It's far from being native ofc (there're weird things going on with colours that I'll test) but it has a nice overlay mac style, no bugs, hotkeys, goes to zero, you can pick the gaps etc.
Anyway I'm using Dimmer extensivelly and even if it is the best solution this cannot replace a native one. Since the brightness is lowered in a linear fashion blacks get crushed the more you lowered it. I think that brightness modes do some sort of clever tricks to achieve an uniform contrast even at lower brightness. I love the OLED monitor and beside this issue, Filevault and HDMI not working everything is great. But for greater compatibility one should pick the XPS 2020, I've missed it but hey, goot to know for the next one