Until recently, if you offered a pump that _could_ be controlled by another device (such as a phone) you would have to offer your own "controller" device, even if 99.9% of your customers have a phone already.

So, this companion device is kind of a thing that Insulet had to release. You'll see this with CGM's too -- there's a small companion device sold with the Dexcom G7 (the "controller"), even though everyone just uses their phone.

This is kind of a regulatory quirk; basically from the FDA's point of view you had to have a complete standalone system, that did not include the phone, in order to be able to prescribe it. I think they do not require companion devices any more, it's OK to release something that requires the user to have a phone.