@OliviaD I think for now you either create the gradient using Base64 string or a a gradient image (you can create using PPT). Hope that answers your question 🙂
Hello 🙂SVG PowerAppsWhen i need gradient or something special, i use SVG langage.
My SVG is created with InkScape. I open the SVG with notepad and paste all the code at this adress : https://yoksel.github.io/url-encoder/ to get back a encoded code. The gradient bar is a image with this :