OOT PowerApps has some themes but it's impossible to adapt the colors or to create one.. that could be a good idea
This feature is on our roadmap but has been delayed. It is expected after October 2020.
Will this idea include the app Icon color? I love that you can upload your own icon for branding and theme, yet the colors don't match OUR colors, at least, can we have a WHITE background? So we can use OUR logo / brand / icon to not have it be OFF BRAND if possible!?