It seems like in the end the pinebook pro did get the SPI chip on it, but then they flashed a closed source U-Boot to the eMMC instead which does not allow booting from SD. So it's again a complete pain for the other distributions to help these users.
For the wiping issue, a lot of times I see suggestions to wipe the first few MB of the storage when there's booting and flashing issues to get rid of an old U-Boot, which is exactly what you don't want in the Tow-Boot case.