Choice of filesystem has nothing to do with raid. You can put any FAT32 partition, including the ESP, on a raid1 if you want. You just need to make sure to use md format 0.9 or 1.0 instead of 1.1 or 1.2 so the firmware will still recognize it.
Choice of filesystem has nothing to do with raid. You can put any FAT32 partition, including the ESP, on a raid1 if you want. You just need to make sure to use md format 0.9 or 1.0 instead of 1.1 or 1.2 so the firmware will still recognize it.