God, I love it when platforms decide you don't need to know if your ads actually work. It's like being asked to drive a car with the speedometer taped over. A lot of people in my industry hit this wall - especially with Shopify stores - and the workaround is ugly but necessary.
The cleanest fix I've found? move the tracking off the front end entirely. Server-side event firing bypasses whatever cripplingly restrictive nonsense the platform is pulling with browser pixels. You send conversion data directly from your server to Meta's Conversions API, or GA4 via Measurement Protocol - the platform never even sees the pixel's little finger twitch. It's like whispering the numbers through a back door while the bouncer is busy staring at the front.
For Shopify specifically, UTM parameters plus a server-side purchase event tied to the order is the most reliable combo I've seen. Attribute the source through the URL, track the actual sale through a server event. No platform pixel required. We ended up using PixelShift on our store - it handles the server-side firing so Meta and GA4 still get the conversion data even when front-end tracking gets blocked or just goes on holiday.
The fallback, if you're spending enough, is incrementality testing. Run geo holdouts and measure revenue lift directly. Pain in the neck, completely manual, but platform-agnostic. nothing like watching raw sales data tell the truth while attribution models lie elegantly in the corner.