Given how easy Framework are to open, not sure if we need this via a USB port. Mobile phones need it due to most being glued shut these days.
But a reflashing header on the FW16 mainboard would be great. At least for the FW13, there isn’t one. It has an EC debug header on the mainboard, and even via a USB port. howett.net/posts/2023-04-framework-ec-card. No reflashing through these, though. To recover a faulty flash, you need to use a flash programmer and pogo pin adapter on the chip. community.frame.work/t/how-to-prepare-for-reflashing-firmware/31001. So yeah, just a header would be a big step up.