One cool thing is include the ability to produce alternate colors on rows within a gallery to give more life to the UI. Just an idea
I agree this is needed.
The app I'm building now is a high-density list that patches directly to SharePoint (using controls in the gallery), so generating row numbers is not a workable solution for me.
TemplateFill = RGBA(RoundDown(Rand()*(220-10),0),RoundDown(Rand()*(220-10),0),RoundDown(Rand()*(220-10),0),1), this Should work for alternate colours in each row
Another solution, if you don't want to deal with a collections:PowerApps Alternating Row Colors in a Gallery - YouTube