I've got some insights to share regarding the applications that can be integrated with QuickBooks Online.
There are various apps that can be integrated into QBO, these can be found on our Apps site. All applications seen on this site are ready to be connected to the system.
However, if you're not able to find Power BI on the said site, I recommend reaching out to our Intuit Developer Team. This team is the best resource for such inquiries as they do app development, integrations, and programming. They can provide information regarding other ways to connect the app.