Android's Privacy Sandbox has a feature called Attribution Reporting. It's similar to the iOS SKAdNetwork. What it does is let you, as ad buyers, get direct feedback from Android about how well your ads are doing. You can track if users saw or clicked on your ads and then what conversions they completed across ad buyers in a 30-day window.

MMPs can also use an SDK to help set up the Protected Audience feature. This helps them manage groups of users that you might want to retarget, on behalf of you or your ad buyers.​