Downloaded 20.08, uncompressed .xz, used Etcher to write SD, booted from SD, but the process did not install on EMMC, but on SD. What did I do wrong? 
Addendum: in the initial boot message I get "Loading Environment from FAT... Unable to use mmc 1:1... In: serial"

Addendum: in the initial boot message I get "Loading Environment from FAT... Unable to use mmc 1:1... In: serial"