"Roll!" arose from an idea I had in the mid-2000s. I had an idea that one could shake their phone to seed the random number generator, just like a dice box, or a fortune-telling toy. Also, most computers only produce pseudo-random numbers; they aren't truly random. But you, shaking your phone, are an external source of data that the computer can't predict, and the accelerometer sensor in your phone can use that shaking motion to seed the random number generator.
The short answer is it's unnecessary, I'm the only developer, and it would be a poor user experience.
App stores take a big cut, so, to keep the site running and maybe be compensated for my time, I'd have two choices: find the magic price point where enough people pay for it so it pays for itself, or make it ad-supported, maybe with premium features. I don't think a magic price point for this exists that would not result in an operational deficit. I've yet to see an ad-supported app where the ads weren't annoying, deceptive, and intrusive, and it's getting worse all the time. I'm building for fun, not frustration.
Accelerometer support doesn't need an app. Websites can access your phone's sensors. If you like the shaking feature, you can give the website permission, and if you don't, you can tap on the screen in different places to "shake" the dice. It's less random, but this site is just for fun; it doesn't need true randomness, unlike blockchains or Cloudflare. The shaking feature is more for the experience, and the opportunity to educate about randomness.
Hello! I'm a GenX career software engineer who wanted to build something cozy and fun that people could enjoy with friends and family.