Add Lumetri (or Camera RAW) based more precise color correction
Premiere Rush need more precise color collection feature such as:
highlight/shadow lightness control
precise HSL control (adjust colors/brightness/saturation specific hue range colors)
Reduce noise (it must be heavy task but it would be great. I never see mobile app having this feature)
Add noise (grain)
shadow / highlight colors
More vignette control
Also I have noticed some parameters is totally different behavior with Premiere Pro's Lumetri effect.
Lumetri is an oblolute must.