Ad platforms don't share who saw an ad, so view-through attribution can't be rebuilt from your own data. What you can do is look at what the platform itself reports, next to your click-based results, and judge the gap.
When Meta spend sync is connected, BrainyMetrics pulls Meta's purchases, purchase value and leads per ad, split into 7-day click and 1-day view. They appear as separate platform columns in the Attribution report. Because Meta also claims sales that another channel closed, these numbers are never added to your totals.