After some quick research online,
1. 144Hz should be supported by Mac Studio with M2 Max (or above) or by Mac Mini with M2 Pro (or above, when it's released). It is my understanding that no other Mac Studios or Mac Minis support it.
2. True Tone, again from limited research, is limited to Apple-made displays only.
Sources:
The number of external displays you can use at the same time depends on your Mac model and the resolution and refresh rate of each display.
support.apple.com
The number of external displays you can use at the same time depends on your Mac model and the resolution and refresh rate of each display.
support.apple.com
True Tone technology makes the images on your Retina display and Touch Bar appear more natural.
support.apple.com