Great write-up! One extra detail that might be worth including in the block device/storage section is that Firecracker doesn't yet pass through discard (trim) from guest to host (as fallocate(FALLOC_FL_PUNCH_HOLE) if file-backed) like qemu?

The fast/efficient asynchronous io_uring backend now in released Firecracker makes it a good alternative for full-sized VMs as well as the original short-lived micro-VM use.