We are facing slds modal issue in SF1. So we are going to fix using lightning:overlaylibary. As per our salesforce document, it was supported in Lightning Experience, Lightning Communities. We have tested it in salesforce app, its working fine to us. Unfortunately, they are not mentioned is supported in salesforce app.
url : https://developer.salesforce.com/docs/component-library/bundle/lightning:overlayLibrary
Our question is can we implement this at real time in salesforce app?