Glad you have it working, On a personal recommendation, i would recommend you take a look at using PARTUUIDS as a form of indirection, so that the same image you create can be used to write and boot from any storage medium without having to worry about what type of storage medium your target is using and the kernel naming convention for it. Mender stores the device names for A/B in the image.
The motivation for this, was that a single image can be used to image different types of devices and VM’s irrespective of the storage, i.e USB, NVME, SATA, PATA, SCSI, EMMC. Its helpful for testing as you can image a USB stick and boot PC from it.
The partuiids can be anything you like as long as they follow the PARTUUID naming convention and each PARTUUID is unique.
I use the following:
MENDER_PARTITION_SCHEME="gpt"
MENDER_ENABLE_PARTUUID="y"
MENDER_BOOT_PART="/dev/disk/by-partuuid/26445670-f37c-408b-be2c-3ef419866620"
MENDER_ROOTFS_PART_A="/dev/disk/by-partuuid/26445670-f37c-408b-be2c-3ef419866621"
MENDER_ROOTFS_PART_B="/dev/disk/by-partuuid/26445670-f37c-408b-be2c-3ef419866622"
MENDER_DATA_PART="/dev/disk/by-partuuid/26445670-f37c-408b-be2c-3ef419866623"