I couldn't get "act timer mytimer" to work from any programmatic venue -- macro, do_file_commands, alias or tellchannel. The only way I could get it to work was by typing directly into the chat window. You can always use your private URL Helper channel to send a tell for ACT, if you don't want others to see the text. The URL Helper will ignore anything that's not a URL or the fullscreen windowed commands.
Crushing, Disruption, etc. can
be monitored, but it would be similar to the harvesting stats page on the XP bar where you have to mouse over the area to initialize them. That data is coming from the Character window, and that was the only way I could figure out to channel those stats remotely. So the snack stats can probably be monitored and alerted the same way, but would require the mouse-over thing (which I seriously dislike) to initialize them.
Snack durations don't appear to be affected by modifiers such as the blessed sapling berries, so it's possible a flat timer could be added to the gear buff macros window if you don't want to use the countdown timer that's already in the UI. Gear buff macros would be a good place for this since you can consume the snack directly from the button and the window already has an alert mechanism. (But if you cancel the snack or it gets debuffed, a simple timer won't know it since it's not connected to anything stat-wise.)
Or I guess we could make a new window and call it the "Snack Bar?"