We are all setup and running tests in GB (synced with GA4/BQ. But is it possible to also see the how the different variations in GA4 are performing? Or do all analysis have to be done through GB analysis?

The events are being passed to GA4, so you can use that with some of the advanced views - but keep in mind that GA4 has no statistics

Do I need to configure something in GA4 in order to see the variations there?