Technologically, what you're looking for seems very straight forward. However, you'll need to determine the legality of offering a raffle. In the USA, it's considered a lottery/gambling and tightly regulated. From what I can see in a quick internet search, it's not legal for for-profit companies to have a raffle, but a not-for-profit may be able to hold an online raffle in some states. Here's a link: https://chance2win.org/us-state-online-raffle-legal-rules/
I'm guessing the legal issues are why you don't see any apps available. Can you tell us more about your business and what you're accomplishing with a raffle? There might be a sweepstakes option (also a regulated industry) that would be more viable.