+1 from me as well for auto-connect alsa, joystick, raw-usb, hardware-observe and shutdown to plex-htpc since are clearly needed for plex-htpc to properly operate. +2 votes for, 0 votes against, granting the requested auto-connections. This is now live.
@tamas I do not see joystick not shutdown plugged yet in the latest plex-htpc uploaded revision. Are you planning to add them soon? I have granted the declaration anyways but let me know if you are not willing to plug them anymore so I remove them.
Also, as pointed by @Igor please add details into your snap description so users can expect these interfaces will be auto-connected. Thanks!