There are actually three options:
"=y"
"=m"
"is not set"
..nothing will be done if "is not set" is chosen.
Note also that the majority of the drivers compiled with "=m" are available in the extensions named *-5.10.3-tinycore64. There are a few drivers in the base contained in modules64.gz (corepure64.gz = rootfs64.gz + modules64.gz).