The definition of an End Product by the PTCRB is that it must utilise one of these physical interfaces:
"Physical Interface - If a physical control interface is required for the End Product, it shall utilize one of the following: USB, PCMCIA, Compact Flash, MMC, RS-232 (DE9), or IEEE-1394. No other physical control interfaces are acceptable."
"Physical Interface - If a physical control interface is required for the End Product, it shall utilize one of the following: USB, PCMCIA, Compact Flash, MMC, RS-232 (DE9), or IEEE-1394. No other physical control interfaces are acceptable."
http://www.ptcrb.com/wp-content/uploads/2020/05/PTCRB-PPMD-3...
Curious how an M.2 based connector was allowed here as they are explicitly called out as connectors allowed for PTRCB modules, not end devices.