I can see that HA does have support for Thread/Matter, and since that’s the way the whole eco-systems are going I think standardising on that (or looking into that for future compatability) isn’t such a bad thing.
… However, I cannot find any resources on devices that might be able to act as both Zigbee and Thread/Matter repeaters… I know the protocols are very similar, and that the HA-Yellow type thing can do both - but I think that I need more zigbee repeaters - but I think buying them when they will be phased out for Thread/Matter devices is a bit silly.
… Are there repeaters out there that work with both of the protocols (and work with HA) nicely?
While they’re similar they are very much not the same and in either case devices will only repeat for the network in which they participate… Which Thread and Matter can only join thier own networks.
They can (virtually) share coordinators using the Matter multiprotocol addon for the Skyconnect device allowing the coordinator stick to simultaneously act as a coordinator for both networks. But that is very different than repeating or routing for each. You will plan each separately.
Yes you’re probably right that all signs point to matter. But understand very clearly - you are very much in early adopter territory there as there’s still a lot of interoperability kinks to work out. While it’s better than it was this time last year. I, for one only own one matter device and it and the Skyconnect I bought to drive that network are still in the box until I feel the solution more mature.
There were early promises of devices getting upgraded to make them matter compatible but that’s been few and far between and honestly for manufacturers it rarely makes economic sense for them to provide the upgrade rather than a new device. And promises of upgrades to hardware to support matter have been left mostly just promises.