Hi,
OOSv4 is licensed under GPL, supports driver Intel HDA PCH drivers which Librem13v3 runs, and Linux Kernel 4.15+. Not being able to find packages from PureOS repository.
oss4-base
oss4-dkms
oss4-source
oss4-gtk
I couple of key advantages to using OSSv4 over ASLA was taken from the ArchWiki is a more minimalistic interface and a simple API to use.
https://wiki.archlinux.org/index.php/Open_Sound_System
http://manuals.opensound.com/devlists/Linux.html
https://packages.debian.org/source/sid/oss4