Awesome! I am dealing with a projects management App that has a lot in common with yours 
In terms of requests / advice / extra feature suggestions, we could think of :
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A visual priority management (like what chrishoward did in its My Bullet Journal app)
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A flowchart-based picture to show the task status, so we can see the past steps and the steps remaining (https://www.presentation-process.com/wp-content/uploads/color-steps-of-process.jpg) though it requires to create our own pictures and store it online, and to put the “status” modification possibility in the modification button on top right of the screen
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A collaborative set of options (possibility to assign a taks to one person or more, the comments component for each task and each project, etc.)
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A Calendar view of the tasks with a color code to specify the project concerned. And if used with a “Public with email” sign in policy, this Calendar view could be filtered by signed in user in order to only show the user’s tasks and deadlines!
I must admit that I have a “project management” App orientation (more than a personal todolist one) 