FYI Although not officially, the Debian metaframework Buster AMD64 distribution might be the first to support native installation of Reiser4 SFRN 5.1.3, kernel and reiser4progs 2.0.3, file system utilities.
I have already made a couple of successful Metztli Reiser4 SFRN 5 native installations onto ~100 GB slices, which root file system is formatted in 'Reiser5' and 1 GB /boot in JFS.
https://metztli.it/reiser5 (Screenshot 600x338 size)
The upgraded netboot installation media metztli-reiser4-sfrn5.iso is available at:
https://sourceforge.net/projects/debian-reiser4/
as well as
https://metztli.it/buster-reiser5/metztli-reiser4-sfrn5.iso
https://metztli.it/buster-reiser5/metztli-reiser4-sfrn5.iso.SHA256SUM
Likely the brick/volume feature(s) will be useful in Cloud fabric infrastructures, like Google's, where reiser4 excels.
The current SFRN 5.1.3 -patched Zstd -compressed kernel in the installation media is Debian's 5.7.10.
The installer defaults to create the root system reiser5 -formatted partition as:
mkfs.reiser4 -yo "create=reg42"