Technically, it does provide better connection speeds by enabling the router to avoid channel hopping, so it can talk to multiple devices (or the same devices if it has multiple antennae) at the same time. This is part of the recent wifi6 and wifi7 standards so more and more devices will start to gain speeds using this technique
Realistically computers have at best 2 antennae and this is largely marketing wank.
Sure, but this isn’t that. That requires actual work put in developing and simulating the product, these are just multiple antennae for multiple channels.
Source: trust me bro I work in semiconductors at a firm that creates RF chips