I believe TBR V1.3 is a necessary, but NOT entirely sufficient requirement for things to join the same Thread fabic - Even having all TBRs @ V1.3, doesn't resolve the credential sharing issues, as I understand it. - Specifically, see: Why Thread is Matter’s biggest problem right now - The Verge
From this article:
- To form this shared mesh, border routers have to be using the [Thread 1.3.0](Thread 1.3.0 makes Thread border routers Matter-ready - The Verge) specification. As of today, most are (Excluding Amazon).
- Next, these border routers have to share credentials with each other — similar to using a password to join a Wi-Fi network
The #2 is the problem part, and an CAN work, if you run the device inclusion from a IOS device, with both Google Home installed, as both TBR can (and do) access the same IOS keychain for the credentials, but I don't think this works from an Android device, as there is not Apple Home application that doesn't run on IOS - From the same article:
*Google’s tells me that “Apple and Google Thread border routers can share the same Thread network by leveraging the iOS Thread network APIs.” So, you could have a Google Nest Hub Max and an Apple TV join a single Thread network if you set them both up using an iOS device. *
However, the same is not true in reverse because an Android phone can’t access the iOS keychain, and there is no Android app that will set up a HomePod or Apple TV (and probably will never be).
My matter network (including HE) is all using the Apple _meshcop._udp nn= entry (the TBR is a HomePod mini - Seems to work fine from HomeKit and Hubitat) - I'm going to try and "force" my Google Nest Hub to join (which I've never really used with matter yet), by loading the Google Home app on an IOS device that's part of the matter network - I've just never tried to factor the Google Nest hub into this, and it's clearly off on it's on TBR fabic at this point (per the mDNS entries for the Google Hub and Apple HomePod mini - Both are showing up as TBRs under _meshcop._udp, but they have different nn= entries (and have both been active for months - So waiting a day, didn't solve this)
Bottom line, I think Thread V1.3 requirement is part of it, and Amazon is clearly totally out of this with V1.1 - But as I understand it, V1.3 doesn't completely resolve credential sharing, and it's still being worked on, given all the combination of different TBRs (SmartThings, NanoLeaf, etc.)
Again, @jvm33 thanks for the great mDNS pointers to "Discovery" and "Flame"