Ack on lxc and minixfs. Do you need minix partitioning as well, or is the fs enough?
While searching config options for "minix" I saw that option about subpartitions but couldn't really understand what exactly it would do.
Perhaps though, once minix would be included, it should be considered if the option would be of any need or benefit for anyone in general - in proportion to its "cost".
Also it might be considered to have a separate extension for minixfs if it would be deemed enough of an advantage to keep filesystems*.tcz smaller, depending on final difference in size it would account for.