Even if you just hired someone to, ignoring UX altogether, do a pure UI pass to just make it look pretty - it would probably be significantly more likely to go viral. My initial instinct looking at this, without having touched the product at all, was immediately that "this is an ugly app for nerds" and I figure that (dumb) issue would keep it from really going mainstream. Luckily I'm a nerd, so I'm willing to put up with it, but don't listen to the other nerds here who think that it's fine as it is—they're not a credible source for how real people will actually react to things, and there's a reason why all the popular apps you probably do use look polished, it's because the ugly ones don't survive, regardless of what visually obtuse nerds think.

I've mostly had success getting design help from friends who are designers (for my current app, I have an experienced designer friend who works 3-5 hours a week prettying up the UX that my engineering team puts together) and immediately everyone we interact with thinks our app is super sexy, the best, and want to use it even if it's less capable than what they were using before, despite us not really having invested that much into design (I'd link it, but it's a B2B enterprise app with no public face).

Where to find designers: I've mostly had success from my extended network, but there are lots of talent on Upwork, Dribbble, and definitely there are people who really are good; but unfortunately there's also a ton of people who have no idea what they're doing, and unless you have some way to vet them, you'll have a hard time wading through the noise. With design, it seems that practitioners either "got it" or they don't, and if you don't, you'll probably hurt the project you're working on more than you'll help it (wasting development time for something that ultimately isn't even a benefit to users/business).

There's also expensive talent aggregators like Toptal, though haven't really used those before. I also see new talent aggregators like Pallet [1], which looks interesting, though no idea how good those are, and not sure if you're prepared to pay the entry fee.

I mostly appreciate designers who:

- are able to explain why one design is better in terms of actual usability + business impact, not just because they think it looks nicer

- can make designs that are flexible to the real uses of users - e.g. don't make a design that only works on mobile or only works on desktop, whatever they come up with can deal with both if your users will use both (which this app definitely would)

- make designs in a methodical way, i.e. viewing the UI as a system that you can set general guidelines on. The spatial/visual relationships between elements is a reflection of how different information in your app relates to one another, not just a purely aesthetic thing (aka "Information Architecture")

- are able to communicate the work clearly; usually that means well-annotated wireframes in Figma for my team, and are available to do some live visual QA sessions when things are unclear.

- can prove that they are able to make steady and incremental progress at least at the pace that my developer team can keep up with, i.e. we're not blocked on design work. My current designer can do that with just a few hours a week. His rate is admittedly expensive, but the results with so few hours are undeniable.

Hope that gives you something to work from!

[1] https://ridd.pallet.com/talent/welcome