Installs just fine however :

t#
t# add-apt-repository contrib
Traceback (most recent call last):
   File "/usr/bin/add-apt-repository", line 95, in <module>
     sp = SoftwareProperties(options=options)
   File 
"/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", 
line 109, in __init__
     self.reload_sourceslist()
   File 
"/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", 
line 599, in reload_sourceslist
     self.distro.get_sources(self.sourceslist)
   File "/usr/lib/python3/dist-packages/aptsources/distro.py", line 91, 
in get_sources
     raise NoDistroTemplateException(
aptsources.distro.NoDistroTemplateException: Error: could not find a 
distribution template for Devuan/chimaera
t#

So thats a no-joy. Likely a trivial tweak required there for Devuan.

--
Dennis Clarke
RISC-V/SPARC/PPC/ARM/CISC
Four decades in production systems.