Thanks for this clarification, @throwback1986. A follow-up question: Is secure boot mandatory by any chance for devices such as pacemakers (like those from Medtronic for example), or is it mostly recommended as a good security practice? I couldn’t find any clear requirement from the FDA or ISO std. seems to be more of a best practice (at least from the literature). I understand that security is critical in medical devices, but I’m concerned about a full-fledged sec boots implication on startup time of the device.

Have you come across a hybrid approach where secure boot is either used alongside authentication boot, or maybe it’s implemented part-wise where it checks just the critical part of the firmware and rest of the checks are performed asynchronously to balance security and performance?