It's much easier to get people involved (even if it's just to give you advice on how to fix things) if they can use the app.

That really helps me get to the finish line, because I'm not thinking I'm going to launch the app in this state. I'm just trying to get it to the next checkpoint. Either I fix the UI/UX or get other involved who can.

Alternatively, UI kits are really cheap (some are free), on sites like ThemeForest, just pick one of those and run with as best you can. There will be rough edges, but for the most part the app will look good enough.