Just noticed Youi Rewards recently added Uber & Ubereats $25/$50 gift codes to their rewards app. 5% seems to be best discount at the moment and better than the previous deal at Suncorp benefits
Other noteworthy discounts I saw are 10% off Ticketek Gift Vouchers and limited time 10% off Myer eGift Cards (normally 6% - ends on 31/08/2019)
Note: You must have at least one active Youi Policy to get access to Youi Rewards.
I have added the full list of Youi Rewards to the Discounted eGift Cards Wiki
AFAIK, no coles or woolies giftcards. Supercheap & bcf are there.