On today screen.
 

Today screen is a personal view, We need it on the projects screen, which is a general view.

What do you mean "Personal view" or "General view" ?
Data is data.
You display same things.
Except that for count of number of activities per project, wich is a calculated value, you don't have it on Project Screen.
And you will never : you will not have calculated values in the project list, for perfomance purpose (some clienbts have thouthands of projects in the list)
 

Thanks for your clarification.
I though that data displayed on "today screen" were strictly inherent to the logged person. But I would like this count in the Projects view, in order to check if there is any project/sub projects which has not been exploded.
Knowing that the count of activities is a calculated values, makes all more clear.
Question: why not having a fixed counter of activities/subactivities in projects?

Because it has very few interest : just select the projet in the project selector and go to the Activity screen to have the count.

And if we add number of actrivities, why not add number of tickets ?
And why not add number of actions ?
And why not add number of milestones ?
And why not add number of risks ?
And why not add number of tickets ?
And why not add number of allocations ?
And why not add number of assignments ?
And why not add number of expenses ?
And why not add number of invoices ?
And why not add number of all objets linked to the project ?

You see what I mean ?