Aven has a non-HELOC credit card with 6% back on groceries OR gas up to $10,000 a year.
https://www.aven.com/rewards-groceries
https://www.aven.com/rewards-gas
Still no sign-up bonus, although I did find a Costco sign-up bonus (really a one-time $135 statement credit) with no purchase required on their HELOC card here:
https://www.aven.com/costco
The 4% back on Costco is a bit misleading because they count the 2% back you get from a Costco executive membership, so it's really 2%, which is what their HELOC card offers anyway.