If we are already entering in weight at the start, our body weight should be a known value

The only useful thing I can think of about bodyweight exercises is to have them NOT decrement weight, but only optionally increment it. But just marking the progression as reps only already achieves this.

Yes, but some movements use your full bodyweight (chin ups) while others use partial bodyweight (push ups) and it would be nice to just indicate ‘bodyweight’ and have the app decide how to handle it.

It’ll probably be something like lats get 100% while pecs/triceps/abs get 50%. That’ll just be background calculations though and you’d see 0 unless you add extra weight.

It’s absolutely irrelevant what portion of your weight you’re lifting with which muscle groups to me. Personally, it’s much more useful to track the total weight; that way, I can keep an eye on my progress with them regardless of body weight.