Why not just note within this documentation for alsa interface itself that
a) the libasound2 needs to be available in the snap’s runtime by being included in the stage-packages, of the part which uses alsa, either directly or through some other package which brings it in. OR ELSE needs to be compiled as a part, if someone wants that.
b) the $SNAP/usr/share/alsa needs to be exposed at /usr/share/alsa of the snap’s runtime by using the layout bind mechanism of snapcraft.yaml. i.e
layout:
/usr/share/alsa:
bind: $SNAP/usr/share/alsa
c) the need for user to explicitly connect the snap’s alsa plug to the snap system’s alsa interface using the below command
sudo snap connect SnapPackage:alsa