Only on GA4 and Firebase so far, starting Meta and TikTok next month. Do we need an MMP now?

GA4 is enough while your paid installs come almost entirely from Google Ads. It logs installs as first_open, reads the Play Install Referrer on Android, credits Apple Search Ads through AdServices, and is strong on funnels and audiences after the install. It stops at the point where several networks claim the same install. It does not referee Meta, TikTok or affiliate claims, send those networks conversions with revenue, give you a cross-network SKAN view, or run install fraud rules, and installs from other networks reach it only if a UTM survives the store. So adding Meta and TikTok is the usual moment to add an MMP. Most teams then run both: the MMP decides which campaign earned the install, and GA4 keeps measuring what users do next. Expect the numbers to differ, since GA4 defaults to a 30-day first_open lookback; align windows before you debug.