It's nothing special really - we run Lighthouse twice (as a GCP Function) on the URL, and using Puppeteer we simply block third-party scripts from loading on one of the runs. Then we compare the results. While this isn't technically the same as running Zaraz on the page, we consider this to be a fairly accurate estimation of the website would work with Zaraz, because on the majority of cases we manage to load tens of tools with literally no performance impact.
Makes sense... I like the idea behind this, and I really hope your startup catches on. There is a definitely a huge need for it.
I can't tell you how many times I've been tasked with UI time-to-interactive Optimization, only to come to find we have great performance without all of our 3p requests. Yet, business/product/marketing don't understand or care, they want to eat their cake, and have it too. It's a terrible situation to be in when you have to report to a non-technical manager.
