From today, 28 October, Meta is adding product browsing to ads already running on Facebook and Instagram. Anyone who taps one of those ads will first see product info and suggestions inside the app, before they land on your online store.
Until now this was an option you could switch on yourself. Now it's on by default, unless you opt out. In its own test, Meta reports 3% more conversions on average. What it doesn't say: whether those conversions happen in your shop or in the app itself.