You should start by following the instructions by Apple to ensure you didn't miss a step by mistake:
https://support.apple.com/en-us/HT210400
Notice that the service changed from "Find my iPhone" and "Find my Friends" to the all-in-one app "Find My..." with iOS 13. Are the "other devices" running the latest software (iOS 13, macOS Catalina)? Is the iPod touch also running iOS 13?