I've been using MacroFactor since January and it's been the best app for me since my main struggle is simply choosing what my calorie intake should be. It doesn't track workouts (by design) but if you consistently log your weight and food, its algorithm tells you how much you should be eating based on your weight loss goal rate, and constantly adjusts as it gets more data.

Yes please! As a frontend dev I'm interested in contributing to the UI or writing my own, but I'm pretty lost when it comes to setting this stuff up to test it all out