How can I check my current data usage/ data balance/ plan usage?

Sim Local app

Go to the My eSIM tab and you can track how much data has been used on the eSIM you have purchased. Tracker is only available on Smartroam plans. 

iOS:
Go to Settings > Cellular or Mobile Service > Cellular or Mobile Data.

Android:
1. Go to the Settings app on your Android phone.
2. Tap on Network & Internet.
3. Tap SIMs.
4. Choose the active eSIM. Here, you can view your data usage details.