What Is a QR Code Pin?
"QR code pin" is an ambiguous phrase that usually means one of two things: a QR code used to display or verify a numeric PIN/access code, or a physical pin-back badge printed with a QR code — there's no single standardized meaning.
If the goal is encoding a PIN or short numeric code, a QR code handles that easily using numeric mode (see Alphanumeric Mode) — just encode the digits as plain text and scanning displays them, useful for check-in codes, coupon PINs or access codes shown to staff.
If the goal is a literal wearable pin or badge with a scannable QR code on it, that's a physical product question (badge printing/manufacturing), not a code-generation one — the QR code itself is generated the same way as any other, then sent to a badge printer.