@Rustler is correct. At the moment, there isn't an option to use a Bunddle Service Item on a time activity in QuickBooks Online (QBO). We can only add inventory, non-inventory, and service items to the Service field on single time activities.
It's a great idea to have a bundled service option when entering time activity. And so, I encourage sharing this suggestion straight to our product development team by clicking on the Gear icon and choosing Feedback. I'll make sure to do the same thing on my end.