I tried this tonight WITHOUT using UTM, only Apple. I used some swift from an Apple sample project that used VZEFIBootLoader() & another sample with the serial console window. And changed the disk image to use same converted CHR disk image (e.g. 1st/boot just changed from EXT2 to FAT16 type, as described in first post) as disk. And CHR still works. Since everyone like icons on Mac included a “teaser”:
The real trick was @kriszos finding here about FAT16 being required by UEFI specs – which is NOT how Mikrotik package the CHR image (e.g. they use EXT2):
http://forum.mikrotik.com/t/router-os-7-on-uefi/156661/5