What about your app is better than what already exists from https://macrofactor.com/workouts/ , https://rpstrength.com/pages/hypertrophy-app , and maybe https://biolayne.com/workout-builder/ ?
All 3 incorporate some form of RIR progression, varying rep ranges, program builders, and (at least in RP) some form of feedback mechanism to tell how impactful the last training stimulus was on recovery.
Not trying to bash it, but to either 1.) help you think through your offer or 2) help you realize there's already a lot in the market.
If you're really just doing this for you, and your interests then glhf :)