Suunto EON Core and Suunto EON Steel can only show one wireless gas reading in the display at a time. You can connect up to 10 Tank PODs to EON Core and Steel but see only one gas at a time.
Learn more about the Tank POD connection from the following sources:
EON Core
Suunto EON Core user guide section: tank pressure.
EON Steel
Suunto EON Steel user guide section: tank pressure.
Suunto EON Steel - How to pair with Suunto Tank POD