If you don’t use a thread, it will render on the calling thread and you won’t be able to cancel or get progress to it in order to display to your users.
To use a thread you’ll have to implement runTaskWithProgressBar in your UIBehaviour subclass.
There’s an example of this just clearing our CI but you can take a look at a rough idea here: Problem implementing runTaskWithProgressBar(te::ThreadPoolJobWithProgress& job)