I want to add a rewards or Loyalty card from my wallet to EUREKA, is that possible?

Indeed it is!  You can access your loyalty card right from the EUREKA  Offers app.

Tap the Loyalty icon in the lower right, then press the “+” button at the top right of the Loyalty Cards screen to add a card. Add a name for the card, enter the card number or scan the barcode on the card.

You can even take a photograph of the card so that it's easier to find it in your Loyalty container. Click on the camera to take a photo of your card.

To re-order your loyalty cards long-press on a card until the drag bars appear on the right.  You can then relocate your cards as desired.  To remove a card, long-press the card and then tap the “-“ icon.