Websites, podcasts, social media, etc. I don't really care about the medium but I can't seem to find a good single source on the subject.
Check with the UFCW, they represent about a million grocery workers nationwide
Check https://www.labornotes.org/ and https://organizing.work/
I remember another source or two, but I haven't checked them so long I forgot what they are. I'll keep looking.
As mentioned by another comrade UFCW is the main union for grocery workers in the US. SEIU covers a lot of other food workers in the service industry. UNITE HERE also covers a lot of service workers, including the infamous Vegas Culinary Workers Union.
You can also follow local IWW news as they will sometimes run independent efforts to unionize local service companies, including food services.