While I'm not a fan of advertising or marketing in general, brands having a presence on the Fediverse would be great for Fediverse adoption, and sometimes complaining about a brand on social media is needed to get proper customer service in this world of AI and bot controlled customer service channels. I can see this being a good thing, and there are some brands/companies I would likely follow. I already do follow a few who are on Mastodon, such as Framework, Pine64, and Raspberry Pi.