I can’t prove that there aren’t any faster units 😆 do you want me to post the specs of every mesh system?
The MBPros, apart from there nTB and 13” 1.4, are 802.11ac 3x3. The newest Extreme is also 802.11 3x3. So they’re a great match.
Many (perhaps most) mesh wifi systems are 802.11 2x2. Here’s an example:
The Linksys Velop is pretty powerful, but it's also pricey and delivered inconsistent test results.
www.tomsguide.com
There’s only so much bandwidth available and running a mesh means that you may be exposing yourself to reduced antenna coverage and/or CSMA/CA challenges.
Some mesh networks will allow wired backhaul between nodes, which mitigates this issue significantly, and may allow full 3x3 for data (same as the peak capability of most of the MBPros). That’s the same though, it’s not faster.
I don’t know that there aren’t any 4x4 mesh wifi 5 networks (I.e., 4 antennae for data). There probably are one or two, but they won’t give faster performance for the MacBook because the MacBook is 3x3. They will just be far more expensive.
A wifi 6 mesh unit would have to be 3x3 for data too, and so far I haven’t seen any. Though I haven’t done much looking. Again a 3x3 Wifi 6 deployments will only be the same speed because the Pro is Wifi 5. Ditto a 4x4 Wifi 6.
Mesh is typically swapping peak throughout for range. Better consistent performance over a larger distance but lower peak performance. Again, if you throw money at it and buy a super expensive deployment it will run as fast as the Extreme, but can’t run faster. (And to be pedantic, faster processor on the mesh unit may result in fractional performance improvements over an older Extreme 6th gen, but we’re not talking about material improvements like 2x2 vs 3x3).