GA4 and Apps

I'm trying to figure out the best setup for GA4 for our television station that has multiple apps — Now app (ios, Android), OTT (all platforms), weather app (ios, Android). The NOW and OTT apps were set up in Firebase connected to legacy GA. I want to add the apps as data streams under one GA4 property, but I'm unsure if I still need the Firebase component or if it can be done in Google Tag Manager or another way.