Booting yocto-wp85 from uSD card


I am working on a custom yocto image with a nginx server and an influxdb database and django genucorn the image size is 40 MiB which exceeds the size of the memory of WP85 which is 32MiB I am looking for a solution for this problem I was thinking about booting from an SD card is what is possible and how to do it knowing that the format of the images yocto-wp85 is .spk how to flash this format on an SD card