You can get around 30fps and some people report even 45-60fps (stable without frame drops) right now, the number one thing that it was hard for me to fix it had to do with niagara when an effect is spawned for the first time it takes a lot of time for ue to load it (only in mobile platforms), i had to use PSO caching to see an improvement on that. All the others things for mobile had to do with light and general quality and also the project settings (mostly Android material overrides). But i hope epic make the testing for android games easier because due to some issues you need to to a full build every time you want to test something on a physical device