Found answer in FAQ:

You can use for the “Scan” and “Pay” function at all of our retail merchant outlets.

For instance, if you buy an ice-cream that costs RM8, but you only have RM6 in your eWallet, your saved bank card will be used to automatically reload your eWallet with RM8 so you can pay for your purchase seamlessly. No need to manually reload while holding up the line at the store!

so i've had tngo wallet installed but don't use it, use boost a lot.

lately boost cashback is whack so wanna try use tngo wallet more.

just wanna confirm tng wallet works like boost right? got cashback and everything?

ps/; i dont have a car, my family car use smart tag.