How are you generating your Participant IDs? If they’re generated through Qualtrics, you’ll be able to use what’s called a “piped text” string. You can read more about them here: https://www.qualtrics.com/support/survey-platform/survey-module/editing-questions/piped-text/piped-text-overview/
There is also some good advice on how to construct sending PPT IDs over to Pavlovia in this thread. I’m currently trying to work out the same sort of thing, so I’m not 100% sure of what works just yet, but this should give you a head start! 