Specialist for BigCommerce + Meta Pixel Issue

BigCommerce + Meta Pixel: events not firing (looking for specialist)
We need someone experienced with BigCommerce -> Meta Pixel / Conversions API to diagnose and fix a tracking issue.
Required experience:

Proven BigCommerce migration work (Shopify -> BigCommerce especially)
Meta Pixel + Conversions API setup on BigCommerce
Comfortable with domain verification in Meta Business and Adyen-style hosted/redirect checkouts

Without hands-on BigCommerce migration experience, please don't apply — this isn't a generic pixel job.
Current setup:

BigCommerce store, migrated from Shopify
Meta Pixel connected natively via Data Solutions (correct Pixel ID, shows as active)
Conversions API enabled via "Set up with Meta"
Adyen payment integration (hosted/redirect checkout)

The problem:

Pixel shows almost no events over the past month on the live store
Only stray PageViews — no ViewContent, AddToCart, InitiateCheckout, or Purchase
"No websites found" in Events Manager
Previous agency couldn't resolve it either; issue persists post-migration

What we need:

Diagnose why events aren't firing / aren't reaching Meta
Verify the pixel actually loads on live storefront (Pixel Helper check)
Confirm CAPI is sending server-side events, especially Purchase through the Adyen redirect
Fix the gaps so full funnel (PageView → Purchase) tracks reliably in Events Manager
Verify with Test Events end-to-end

To apply: Share 1–2 BigCommerce migration projects you've done, ideally ones where you handled pixel/CAPI setup. Generic Shopify or WooCommerce tracking work isn't relevant here.