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. 

iOS:
Go to Settings > Cellular or Settings > 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.