I've enabled several find's features, such as CONFIG_FEATURE_FIND_EMPTY=y, CONFIG_FEATURE_FIND_PRINT0=y and CONFIG_FEATURE_FIND_DELETE=y. All of them appear compiled into the binary, except `-delete`. Is it a bug? A SO question from 2015 also complains about lack of `-delete` support: https://askubuntu.com/questions/583073/using-busyboxs-find-to-delete-recursively-some-files
Hmm, found in option definition that CONFIG_FEATURE_FIND_DELETE depends on CONFIG_FEATURE_FIND_DEPTH. Seems working!