what is the magic dd incantation to copy the system from the sd card to the emmc?

[calinb]

You could probably get Armbian (on emmc) to work
by replacing its uboot with PCM
Not sure, I think PCM is a BSP, separate trust.img???
If you have a usb->emmc adapter
OR,,, as the very last stage of an install

Thanks for your prompt reply, wdt!

My Manjaro system (/ on NVMe) relies on eMMC of course (both Manjaro /boot and uboot are on my eMMC) so I don't think I'll mess around with my eMMC until I get another eMMC module for experimenting. I have the usb > eMMC adapter accessory from the Pine64 store but I never ordered a spare eMMC. The Foresee eMMC module appears to be a non-standard/common design so it's probably best to order the module from Pine64 too.

I remember reading about trust.img, etc. over a year ago, but I don't recall how it works. I'll have to re-study! PCM720 provides the following two files for eMMC/SD installation and, to the best of my knowledge Manjaro has not over-written them since I installed them to my eMMC.

Notes from PCM720's release page: https://github.com/pcm720/u-boot-build-scripts/releases

Writing to SD/eMMC:
# dd if=idbloader.img of=/dev/<mmc> seek=64 conv=notrunc
# dd if=u-boot.itb of=/dev/<mmc> seek=16384 conv=notrunc

Writing to SPI Flash (Manjaro):
# flash_erase /dev/mtd0 0 0
# dd if=spiflash.bin of=/dev/mtd0

If dd doesn't work for you (see #2), try nandwrite:
# nandwrite -p /dev/mtd0 spiflash.bin

As I mentioned, I have only installed the two SD/eMMC files to my eMMC idbloader.img and u-boot.itb). I have not attempted to install spiflash.bin to SPI.