For reasons I don't understand, I've been informed that my 12/24/20 post was my first post. If so, that makes my previous post my 0th post and potentially invisible, so I'm posting it again. Sorry if that's against the rules, If it is, it's fine to delete it.
Situation
ArcGIS Pro allows the user to set the default project to be opened on startup by specifying a path in
Options/Application/General/Start ArcGIS Pro/With a default project
Suggestion
Add a shortcut on the Open/Recent projects list to specify the default project. This would work as follows:
Under Project/Open, for each item the in the Recent Projects list, provide a second context menu item "Set as Startup Project"
On click, set the default project value in Options/Application/General/Start ArcGIS Pro using the selected path