Hey, I'd be interested in your local trello. I was meaning to write a todo-app based on best psych best practices, especially only presenting the highest priority ( = urgent * important) item at any given time. I also wanted to add ordered sub-tasks, due-date, and time estimate features so that the urgency ramps up automatically as the remaining time to complete a task approaches the estimated length of the task.
Sure thing. It's open source and you can find it here (1).
Unfortunately it's very badly written (sorry) because I wrote it just for myself on a weekend and is very limited, just enough to get the job done for me.
You should look at Taskwarrior for some inspiration! I use TW and it has the features you mentioned(and I use them regularly). Urgency is derived from certain coefficients[1].
The problem I have with Taskwarrior is that (from a layman's point of view, i.e. mine) there's a lot of new information you need to learn just to get to the point of a simple TODO. Whereas Trello has the massive benefit of being intuitive and you're up and running in seconds after making the board without even having to read any docs.
Anyway I'd be interested in learning Taskwarrior, but in my day job I work in a team and I can't make them use that kind of tooling.