Hi @CThomas - a great question for sure. What we would normally advise in this kind of case is to utilize a parent/child board relationship. Where basically, all the data resides in a single “parent” board and the individual project (child) boards can be managed individually. The only main difference is these child boards are a series of mirrored columns from the master. This gives you a single board to base your reporting/dashboards against.
The main issue with this approach and what you have detailed is that subitems are not supported (as you currently cannot mirror subitems between boards). You will also find subitems are not supported in many areas of monday. These features are being added regularly
There is an app called Team View, which is amazing and it does support subitems. This can be viewed directly from a board or added as a dashboard widget. This can easily be filtered to show items due today by who they are assigned to. This may solve many of your issues however it does require individuals to be setup in the people column. To get around this, you can setup these individuals with viewer accounts (free of charge) so they are identified within the people column.
This app does come with a yearly cost (~100$ USD) but includes a free trial. It has been a hit with a number of our clients.
Hope this helps!
Mark