Got some users, added a paid subscription. Now what?

I created iCuerpo ( https://landing.icuerpo.com ) to prove that I was capable of writing and publishing an app by myself.

iCuerpo was born as a PWA and it enables people to track their gym progress on any device and in an easy way. After noticing that PWAs have a lot of limitations for iOS, I changed it to a cordova-react app and was able to use push notifications and a screen keep-awake functionality.

Now I feel my app is complete and despite it having a few active users, I'm not sure what to do to profit from it.

My idea is to sell it to gym owners and switch from a freemium model to a SaaS where I charge monthly for the app.

What should I do to go in that direction?

Should I just send emails with an offer to random Gym owners from all around the globe?