Ah, the Kangaroo is similar to my Computesticks.
Consider this data-points or noise ...
1) I can boot Porteus 4.0 from the internal micro-sd card on the older computestick which the manufacturer actually allows to happen. It will also recognize all the *mmc devices. It uses Syslinux 4.06
2) I can put Tinycorepure64 on that micro-sd card, modify/add a section to Porteus' own syslinux 4.06 menu and boot Tinycorepure64 that way identifying the micro-sd card with a UUID.
3) BUT, after boot, one only ends at the ash commandline. Using fdisk -l shows that no filesystems are found.
4) However, if I add an external usb-stick, place my tce directory upon it, and identify it with either a LABEL or UUID, then TCpure64 works just fine - but still no *mmc devices are detected either.
Ie, it seems I can initiate a TCpure64 boot from a micro-sd / mmc device with a syslinux 4.06 bootloader, but once booted, it doesn't know about mmc devices. And, even if booted from an sdX/usb stick, TC won't recognize mmc devices whether one uses the mtd extension or not.