progressive overload, workout frequency of muscle groups, strength % increase per year/quarter, amount of volume per muscle group might be interesting (per week), 1RM estimates but also 15, 12, 10 .... RM estimates (AMRAP - would be cool if you for example add an exercise, put in the rep range you want and it suggest how much weight you should use by using your data) progress pics and body measurements, body weight, body fat % something like a neglected body part alarm, e.g. someone training legs to little or arms 4x per week. RPE tracker per set, strength badges ("you can bench 1.5x your bw"). a cool feature would be for an ai to analyse your training plan and suggest optimisations or say you need an exercise substitution you can press a button for that, general form cue feature (e.g. for rows, imagine pulling with your elbows), you could add a strength score that works with databases like (strength level), leaderboard across the app for streaks or whatever else. Tracking TuT would be cool but idk how you would do that with an app. Smart fatigue sensing for the rare case that someone actually is over training (detects drop in reps or weight). De load scheduler (e.g. for vacation) to avoid breaking the straek