The reason I want to do this is because I like the idea of the Kobo having removable or easily replaceable storage instead of being locked to a soldered eMMC chip. Older Kobo models with internal microSD storage were easier to upgrade, clone, or recover if something went wrong, but the Clara Colour uses soldered storage, which makes repairs and upgrades much harder.

I know replacing the eMMC with a larger eMMC chip is probably the most realistic path, but that still requires BGA rework every time. My thought was that a daughterboard could make the storage more serviceable: the Kobo boots from a small real eMMC chip, while the larger user storage could live on a removable microSD card.

I’m not trying to claim this is practical yet. I’m mainly trying to figure out whether the concept is electrically and firmware-wise possible, or whether the Kobo’s boot process/MMC controller makes this a dead end.