Liquid and shopify dev expert

I'm building a SaaS where merchants upload a Shopify theme ZIP and instantly see a rendered preview in the browser. No Shopify account. No dev store. No CLI. Pure server-side rendering. I've already done the research. I know Shopify's own docs say local rendering "isn't reliably possible" because their Liquid is tightly coupled to their backend. I know the CLI just proxies to a real store. I know all of this, and I'm building around it anyway. What I need is someone who has actually done this or something close to it, not someone who will Google it after landing the contract. What the engine needs to handle All standard Liquid tags + Shopify's 60+ proprietary filters (money, img_url, asset_url, color_darken, handleize, t translations, font filters, etc.) A realistic mock data layer covering ~67 Shopify global objects (product, shop, cart, collection, customer, request, settings, and the rest) Section/block schema parser that reads % schema % JSON inside section files, extracts settings and injects them into the render context OS 2.0 template routing that reads templates/product.json and assembles sections in the correct order Asset pipeline that resolves asset_url calls, extracts files from the ZIP, and serves CSS/JS/images Pixel-perfect rendering on real themes like Dawn, Debut, or Impulse. The preview must be visually indistinguishable from what a merchant sees on a live store: fonts, colours, spacing, section layout, images, everything. If someone uploads Dawn and it doesn't look exactly like Dawn, the engine has failed. Checkout and cart functionality can be stubbed, but the visual output is non-negotiable. What I'm NOT looking for Anyone who will set up Shopify CLI and connect it to a dev store A LiquidJS "hello world" that breaks on real theme syntax Someone who has "worked with Shopify themes" but hasn't built a renderer How to apply Skip the cover letter template. Tell me: Have you built a standalone Liquid renderer before, or something architecturally close? What did you use? Or can you build it? How would you approach Shopify's proprietary filters roll your own, fork an existing library, or do something else? Visual fidelity is the core requirement here; the rendered preview must be pixel-perfect. What's your approach to closing the gap between a standalone renderer and Shopify's actual backend, specifically around dynamic assets, fonts, and theme settings? If you can't answer those three questions concretely, this isn't the right fit.