What I would love to have as an app would work as an overlay - you photo your flower, it's compared with pictures of the breeder's opinion of the plant being at its optimum point, little confirmation noise and down she comes. If she's not ready, the comparison picture will tell you roughly how long left.
I have zero tech skills, the above may be possible, but would surely be very handy.
Leafly is a great app. Lots of good info there. Cannabis News pro I also like a lot. It lists several news sources to keep me up to date. Weed Trivia is fun. Good for testing basic knowledge of cannabis.