The check in Python did not work with devices without kernel variants due to it returning None and that breaking the has_kernel_variants check. Fix that, and also adding the kernel variant to install packages, which was missed. In the process, rename kernels to kernel_variants. All devices have at least one kernel, but not all have "variants" :) Signed-off-by: Pablo Correa Gómez <pabloyoyoista@postmarketos.org> Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/7489>