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Seems kind of chairs to me unless there's more to it than "in-universe companies/businesses/brands exist".
Let's take characters for example. There are many tropes related to basing a character on a real-life person — Write Who You Know, Author Avatar, No Celebrities Were Harmed to name a few. But there's not really one for "this character is wholly original and not based on any real person to any degree."
So by the same token, the fact that, say, the Boonchuys own and run a restaurant in Amphibia that is not based specifically on any real restaurant (other than Thai restaurants in general) is not a trope (that I know of).
You asked about brands, but this is all in the same area in my view.

Is there a trope for In-Universe brands that are not Bland-Name Product, Writing Around Trademarks or Brand X?
Fashion games like Style Savvy, Aikatsu, and the Pretty Series have fictional brands with unique names and unique clothing designs that bring out the characters’ personalities. (In general, most games developed by Syn sophia tend to have lots of fictional brands, and I know that Aikatsu is a Bandai IP.)
You can look at some examples below.
Aikatsu Brands:
https://aikatsu.fandom.com/wiki/Brands
Pretty Series Brands:
https://pretty-series.fandom.com/wiki/Brands