Installing packages for ubuntu 18.04 did it for me.

They have all necessary patches applied to make it work with newer kernels.
No dependencies problems, libraries from ascii are of high enough versions, and it doesn't pull in any unnecessary stuff with it

Just download manually and install.deb files for these packages
oss4-base oss4-dkms oss4-gtk

from bionic beaver repos.

Sysv init scripts are included.

Possibly OSS can not be run with latest kernels.

Another possible reason is perhaps recent patches to OSS could break the kernel module for my audio card.

Very unlikely, although theoretically possible, that this has to do with devuan itself.

Please report if anyone at all is using OSS4 successfully on ASCII.

I haven't been able to get any sound at all while running ASCII through OSS4. The default ALSA setup works ok.

Steps I've tried:
Install latest .deb from the OSS4 official site. Installs, compiles kernel modules, sound card model is identified correctly, but as soon as I try something as simple as 'osstest' I get a segfault and a stack trace in dmesg which goes around "audiopci_set_rate...".
The kernel modules are there, they are loaded and visible in 'lsmod', I even get an annoying 'beep' sound as soon as they get loaded, until I mute the input-channels through ossxmix, which does work. (Same behaviour on working jessie install)  But no sound whatsoever.

The "forward-ported" .deb from jessie doesn't even get to compiling modules.
I tried compiling several versions from source (mostly later ones), but the best I can get is the same behaviour as described above.

I tried on two separate ascii test systems.

ALSA works ok on both systems, but OSS doesn't work and displays identical behaviour on both.

I am currenttly running jessie as my main system since march, OSS4 works perfectly, so I KNOW it's NOT a problem with my sound card. On the working jessie system, I am using official deb packages from jessie repos.

Would appreciate any insight.