I'm not sure if you want to trigger an email for every project so I will assume for example, that only projects with tickets meeting some criteria are deserving of causing the project to be emailed. So my suggestion is to create a summary checkbox field on the relationship between projects and tickets to indicate whether the project has tickets which are deserving of being emailed.
Then you could set up a special form for the project which only has an embedded report of tickets which are deserving of peoples attention.
Set up an email notification on Projects to Fire when a field called [date time to trigger email] is changed.
Then you can set up a Pipeline to run at 4:00 every day, which would search for projects which have tickets deserving of being emailed and populate a [date time to trigger email] field with the current date time. You can put this Jinja {{time.now}} into the field to set the current date / time .
Now, when you say every day, you probably don't actually mean the weekend so one way to control that is to make a helper field on the Projects table notification to indicate whether today is a weekend
DayOfWeek(Today())=6 or DayOfWeek(Today())=0
and put in a notification filter not trigger the email on the weekend.