Interesting timing, Stronger By Science have just made their programme bundle free for every body: https://www.strongerbyscience.com/program-bundle/ Maybe making use of these could solve the exercise selection and programming issues in the app?
That said, they're mostly full training programs i guess, while what Workout.cool or the old Workout.lol project needs is more at the "individual exercise level" let's say. Videos, metadata, structure, etc.
If they ever open-source a library of exercise videos with clear licensing, that could definitely help yep