One use could be to run something like whatsapp to have a virtual US presence if in another country, or maybe have a business number separate from your personal number and use whatsapp web interface to read/send messages.
I have a work and personal phone. For many reasons, it's very difficult to merge everything onto a single device. Further, I really don't need to do much "phone" stuff with my work phone. It's mostly a glorified pager, 2FA, and occasional Slack/Email. Anything serious gets a sit-down on my computer.
This would effectively let me carry a full-isolated, properly segmented work phone without having to carry two devices.
If your employer mandated use of a dedicated work phone in the first place, why on earth would they allow you to use this product to do that?
That’s the thing about this. It creates very clear and strong boundaries which are easily enforceable.
It lets me have a work phone on my personal phone without giving my employer any meaningful access to my personal phone.
That's not a made up use case; I think there are a lot of businesses that fit that description.
This looks like a classic solution in search of a problem.