certified UX designer speaking here, the number one priority when designing an app is to put the user front and center, this is challenging because what works and makes sense to me doesn't work or make sense to a lot of people, this is why we do something called "user research" more specifically "interviews" something that is not possible to do if you're a solo designer, since you'll have to compensate people for their time, this works by watching and interviewing people while they do something you asked them to do, sometimes you need to play some games with them to see what makes sense from their perspective, an example of this is giving them small pieces of paper with words written on them and ask them to put thing that seem related to each other in different cups (useful for designing menus and submenus or a settings page.. etc), there are ways to see how people think about interfaces.. but the point is it's not a guess game and even when we don't have the resources (which a company does) to perform a user research there are ways to know how people will interact with UI, and there are guidelines that are proven to work, why do you think the hamburger menu (three lines stacked on top of each other) is used basically everywhere!

I would say if you want to win the NPCs, AVOID and I repeat AVOID showstopper events, this could be buggy software that prevents the user from accomplishing a certain task, (example: signing in to Signal and not receiving the SMS codes) that's a showstopper, you can avoid that by eliminating the phone number requirement or just offering a skip option to not use a phone number

another mistake I see a lot is using too much text to describe something, STOP doing that Foss devs, use illustrations instead (why do you think tech companies hire illustrators?) drawings help the user understand the message much more quicker than reading a small paragraph