1. Set up a features for your 1,000 true fans. [0]
2. Reduce as much onboarding friction as possible. Prefer passwordless login i.e Phone, OAuth as compared to "username" & "password" combinations. People have enough passwords to remember. Read "Alchemy" by Rory Sutherland.
3. Promote the app via Fitness oriented localities, Gyms, Fitness YouTubers, Running Clubs, Athletes (people serious about playing sports both professional & amateur). Read "The Formula" by Albert Laszlo
4. This is assuming that your app has any actual value it offers. If your app actually offers any value then achieving PMF is simply a Marketing/UX and distribution problem. 2 & 3 should help you with Marketing/UX & Distribution strategies.
5. Get on Android please it's 70% of the smartphone market share.