The vfat.ko module would also be needed then. I would have
thought that's already in the initrd though.
I had to pull: fat.ko, msdos.ko, nls_cp437.ko and nls_ascii.ko from the Debian 12 ISO's own linux-image-6.1.0-9-m68k.deb plus pata_falcon.ko and libata.ko from its cdrom initrd.gz
Try loading that module explicitly and see what log messages you
get. I don't remember having to use any special module options.
Well, me neither, on 2.2.25. ;-)
However I have bumped into another issue: in 2.4.4.6 a breaking change was introduced for my 1GiB GEMDOS partition: bytes per logical sector can be at most 4096 bytes (memory page size) so my 16K logical sectors are rejected by the kernel. So currently, one can mount only a 256 MB GEMDOS partition at most.
Perhaps I'll try to mount an ext2 partition from FreeMiNT. :)