And Handbook Chapter 18 section 8 should be followed by a section describing using exFat filesystems, and FAT32 filesystems.
Please note that mount.exfat is from ports and this request is better to submit to the upstream.
I opened an issue upstream.
% apropos exfat
dumpexfat(8) - dump exFAT file system
exfatfsck(8) - check an exFAT file system
exfatlabel(8) - get or set an exFAT file system label
mkexfatfs(8) - create an exFAT file system
mount.exfat-fuse(8) - mount an exFAT file system
% man 8 mount.exfat-fuse
EXFAT-FUSE(8) FreeBSD System Manager's Manual EXFAT-FUSE(8)
mount.exfat-fuse - mount an exFAT file system