Ugh, that happened to me too. But instead of researching other apps and waiting for them to decide to go premium too, I built my own workout app. Been using it for a couple months now and it's working great, but the hassle of publishing it to the app store means that it will only ever be a solution for me and I can't share it with anyone.
I actually started with it as a PWA, but ended up rewriting it in react-native. I wanted a couple features (heart rate monitor, lock screen integration) that afaik don't work with PWAs.