Is a lean, parallel HTML-to-PDF engine in Rust technically realistic, or am I underestimating browser complexity?

I’m building an experimental HTML-to-PDF engine in Rust and would like technical feedback from people who understand browser engines, PDF generation, rendering, or high-volume document systems. The goal is to build a very low-RAM, highly parallel HTML-to-PDF engine for server workloads. Think invoices, reports, tables, receipts, business templates, generated dashboards, and API-based PDF rendering. The motivation is that Chromium/Puppeteer is very compatible, but expensive for high-volume PDF generation bec