Since I've done quite a few Circle reviews lately, here's some advice if you're applying:
Reviewers mostly just follow the "App Criteria" checklist. Already doing this before applying can save a ton of time during review https://gitlab.gnome.org/Teams/Releng/AppOrganization/-/blob/main/AppCriteria.md
In particular, test your app with a11y options such as large text and high contrast, and try using it with just the keyboard by tabbing through controls.