There is no command to get what you want but I have a script that will get the data for you.
# Purpose: For a Google Drive User(s), delete all drive file ACls for files shared outside of a list of specified domains
# Usage:
# 1: Get ACLS for all files, if you don't want all users, replace all users with your user selection in the command below
# $ Example, Basic GAM: gam all users print filelist id title permissions > filelistperms.csv
# $ Example, advanced GAM: gam config auto_batch_min 1 redirect csv ./filelistperms.csv multiprocess all users print filelist id title permissions
# 2: From that list of ACLs, output a CSV file with headers "Owner,driveFileId,driveFileTitle,permissionId,role,type,emailAddress"
# that lists the driveFileIds and permissionIds for all ACls except those from the specified domains.
# (n.b., role, type, emailAddress and title are not used in the next step, they are included for documentation purposes)
# $ python GetNonDomainDriveACLs.py filelistperms.csv deleteperms.csv
# 3: Inspect deleteperms.csv, verify that it makes sense and then proceed
# 4: Delete the ACLS
# $ gam csv deleteperms.csv gam user "~Owner" delete drivefileacl "~driveFileId" "~permissionId"