I think for Google the more meaningful other brands are the actual product ones, like Waymo, Nest, YouTube, Calico, Verily. Those are the ones that benefit from being able to distance themselves a bit from being "a Google company" and all the baggage that comes with that, eg an assumption that it'll be shuttered at some point, will pivot massively into ads, whatever.

I don't think Meta has nearly that need. It's "other companies" are Instagram and Whatsapp, which are basically in the exact same space as Facebook.