This diff had a section about endianess of newfs. This is not written anywhere that ffs is dependent of endianess.
Related bug report https://marc.info/?l=openbsd-bugs&m=150242795204995&w=2 Index: newfs.8 =================================================================== RCS file: /data/cvs/src/sbin/newfs/newfs.8,v retrieving revision 1.75 diff -u -p -r1.75 newfs.8 --- newfs.8 23 Apr 2019 18:13:11 -0000 1.75 +++ newfs.8 19 Aug 2019 15:49:15 -0000 @@ -345,3 +345,8 @@ The .Nm command appeared in .Bx 4.2 . +.Sh CAVEATS +The created filesystem can only be mounted on systems running architectures +of the same endianess as the one on which +.Nm +has been used.
