Places that only exist for apps: store nominations, in-app events, public betas and app communities.
Read the self-promotion rules first. Posts that show the app with a short video and ask for feedback do best.
Post: Show what you made and ask for feedback. Follow the community rules on self-promotion.
This one lives inside the store or an app community, so it only applies to apps. In the workspace, Groivo gives r/iOSapps its own App Store campaign link (ct=) and Google Play referrer, so downloads from it show up in App Store Connect and Play Console.