+1 from me for auto-connect of the following interfaces as these are required by the grafana-agent snap for it to operate as expected:
network-bind
time-control
hardware-observe
mount-observe
network-observe
system-observe
Regarding the requested system-files interface - can you be more specific? /var/log/ should be accessible via the log-observe inteface, and parts of /proc/sys/kernel/random are already in the base template for all snaps.
However, I don’t think either /proc/mdstat or /proc/schedstat are currently covered by any snapd interface - both of these seem like reasonable candidates to include in the existing system-observe interface so perhaps a PR to upstream snapd to includes these there would be a better option?