I believe that is technically possible now with the AppSheet automation feature. You could create a daily Schdule Bot to run say every day at 1:00 AM that adds new records for all those tasks where the bot runs where the day of run is greater than or equal to [Start Date] and less than or equal to [End Date]. So the bot would add new records on a daily basis for all open tasks rather than adding all records at once till the end of the respective task.
So the schedule bot runs a process of Run a Task → Change Data – > Add New Rows.
While creating the first task first time, the employee could define start and end dates. And the daily bot will copy certain fields ( Say task name and description, the project name etc) to create a new row each day.
However, @prithpal or someone from the AppSheet automation team or other community colleagues may opine on the suitability of adding a high number of rows on a daily basis this way using automation. I tested have the concept wherein I conditionally add around 3 or 4 rows. Also, I ran the schedule bot in test mode as my test app was not deployed.