Works very well now and is being worked on constantly.
Mac mini M1 -> USB-C to Display Port cable -> LG 27UL650-W
Controls brightness and contrast of display, and also controls the headphone jack volume.
When my MBP is put to sleep and wakes up, third monitor brightness cannot be controlled. Also, NightShift does not work anymore on my Apple Thunderbolt monitors after the install. Both 2nd and 3rd monitors are Applet Thunderbolt.