Ask HN: What ways are business dba (doing business as) names used?

This isn't a "how do I do it" question - it's more looking for experience, personal or professional, on how you've seen dba's being used. I'm personally interested in analogues/how other countries handle this but believe the location/scope to be USA-specific. To explain the question, it seems like a dba can serve different functional purposes:

For example, a business formed under the name "Acme Coder LLC" may claim and utilize the dba "Acme Coder" just so they can drop LLC for signage/ads etc.

But a dba can also be used for industry-purpose naming, e.g. "Acme Coder LLC" wants to diversify and offer design services so they register and utilize the dba "Acme Coder and Designer".

As I understand it there is no limit to the number of dba's a business can register and utilize. In theory, there's nothing stopping, "Acme Coder LLC" from also registering and utilizing "Acme Pizzeria".

So just curious if there are any interesting or notable usages of dbas anyone has. Or if a dba is purposed to offer a new product etc.

This question is just coming from an angle of personal and professional curiosity. A current tech example of how this topic comes up may be the company that sells the Rabbit r1 - believe coffeezilla mentioned something like the company was previously named and operated-as a crypto company before pivoting.

Finally, it seems reasonable an entrepreneur would establish "Acme Parent Company LLC" as a main business and pursue different ventures through dba's such as "Acme Venture" and "Acme Venture 2" - is this actually done?

Thanks for any commentary or discussion on the topic.