Found today that the current apple-boot-firmware installed with fw_update works.
Built my own backing out the most recent changes, but then noticed that the boot.bin from current fw_update package was different than the boot.bin in my efi partition. File hashes below if they're useful. pkg_info showed v 1.3 installed with the failing-boot.bin file. SHA256 (failing-boot.bin) = f78c547db8e9a5193c2f1c8d9c89b1f35f57e2a8c87fb67e2e83c3bae60c1e45 SHA256 (1.3-now-boot.bin) = fa892b057949648dd7f562efeae7a46939f787b4b664a9e79bf2ea73fc3fbc33
