Many ads influence people who never click: a video watched in a feed, a banner noticed on a news site. View-through attribution tries to capture that by crediting conversions that happen within a short window after an impression, typically one day.
Only the ad platform knows who saw an ad, so view-through numbers come from the platform itself and can't be independently rebuilt. Platforms also tend to claim conversions that other channels drove. The sensible approach is to look at view-through numbers next to your own click-based results, never added to them, and to ask customers how they heard about you.