Waveform and vector scope can help us to analyse color. Almost all the composing software have these scope, but I only see waveform in Affinity Photo. I don't know why image editing softwares don't support them, they are very useful in VFX, photography,architecture visualization, etc.

Open source software Blender 3D also have waveform and vector scope, maybe Krita can refer to it( I am not programmer, so I don't know if bring them from blender to Krita is possible).

"I don't know why image editing softwares don't support them"

If some feature isn't implemented, it's simply because nobody has had time for it... I guess Natron has these features as well, since it supports OFX plugins. As for me, I never have heard of them, and I don't really feal like they would ever be any priority for me to work on... So you would either need to learn to code, or find someone who wants to implement them. (Or implement support for OFX plugins, of course.)