Yes, we understand, this requires a not insignificant change to both of our mobile apps, They are currently on a separate unrelated development cycle, when that is finished, we will likely review an implementation.
For now we are concentrating on matter's 1.6 version which supports TBR discovery and key sharing without going through the current 1.5 mobile device keychain workarounds...
I understand your priorities and agree.
Yes, please! 
My understanding of this keychain problem is that it's not Thread Tools who can fix this. They need a lot of security information that only Hubitat can provide. That takes time and effort.
See Mike Maxwells' reply to my post.
HAL9000:
I finally managed to pair the Grillplats with Homekit... which automatically adds the device to the Eve app. I have attached 2 screenshots from Thread Doctor that clearly show the Grillplats using the Hubitat network and acting as a router in the thread network. The Grillplats appears in the upper right side of the Thread Doctor topology diagram.
That's likely never going to happen with the spazplatz, i made a post about it someplace a few days ago. Bottom line: its asking for a bluetooth stack option during comissioning that we don't currently support, and right now we have zero plans to modify our bluetooth stack.
I have reproduced the scenario @donkrell describes above and am 99% confident that I now have an IKEA GRILLPLATS participating in the C-8 Pro T's Thread network, as evidenced by the device's IP address corresponding to the Hubitat's Thread OMR.
What I don't know for certain is that the plug is now a repeater in the Hubitat's Thread network, but it seems that it ought to be. If so, I've now got 12 Thread repeaters to deploy.
Nitty gritty details if anyone wants to repro (and they aren't pretty)
I have an Echo Dot (5th gen) from 2022 and Echo Show 8 from 2022, as well as an eero Pro 6 network. I can't tell you for sure which one did the work because I had all three, the plug, and my iPhone within a few feet of each other.
I did Add Device in the Alexa app. I was unsuccessful trying to take any shortcuts such as adding by device type or brand (which somehow don't ask for a scan or setup code). The success came when I chose Other at the very bottom, then indicated it had a Matter logo. I scanned the QR code on the device and the app indicated it was found and Alexa was getting it ready. I was prompted for which Thread network to connect to and given the choices of Hubitat or Apple Home (I have Thread turned off on eero).
The device add completed but it said it added some random device already existing in Hubitat and Alexa (e.g., Dining Room Chandelier). That's bizarre. I went into Devices in the Alexa app and actually saw two new devices - something like First Device and First Plug. At this point, the plug was on Hubitat's network, but not visible at all in Hubitat. I clicked on "Other Assistants and Apps" on one of the two, and selected Hubitat. I got the setup code, and added to Hubitat using that. This process is a lot like sharing a device from another TBR, but the device's Thread network is Hubitat's already. Makes my head hurt. But I think it worked.
HAL9000:
Your experience is very similar to mine.
I'm not sure why Alexa adds a second device when pairing an outlet, but I've seen that behavior with several devices besides the Grillplats. And one must use that second device to generate a setup code in order to pair the device to another application such as Hubitat or Homekit.
If you look at the attachments I included in my post 186 you can see that the Grillplats is labeled as a router. The Eve app also calls it a router and so does the Home Mapper app that runs on a Mac. I'm not sure its a very good router. It's a bit slow to respond to on/off commands. But Thread Doctor and Eve both show the Grillplats with multiple connections in my thread network.
I'm glad I don't have 12 of these problem children.
I really appreciate your discovery of this workaround.
Getting them paired was indeed problematic, but I hesitate to call the plugs problems. There's been nothing shown to indicate a fundamental issue in operation, and the BLE PASE timeout only occurs with Hubitat, and not with at least two other Thread commissioners. Hopefully, that will get resolved soon.
I have 3 GRILLPLATs included into my HA (openthread) managed thread network. I've also shared them directly with Alexa and ST via Matter. They seem to route just fine and report power as expected.
I also have one of the TOFSMYGGA outdoor versions, and it works fine too.
I assume you mean that you commissioned it originally on HA, and had no problems onboarding it to the HA Thread network. That's yet another success case (Apple Home, Alexa, eero, and HA) where the PASE timeout does not occur.
We can stop complaining about the spazplatz commissioning and Hubitat, the root cause has likely been identified and for reasons already explained resolving this devices issues with Hubitat isn't in the current workflow.
Noted. And I don't intend to repeat any information already covered in publicly visible threads. However, the statement that ...
.. does seem to invite a response with the converse that other commissioners don't have the issue. But point made, we'll move on.
In fact, I've spent a couple hours this morning working on the workaround to get the device on Hubitat's Thread network. I will document that once I have a repeatable process.
Calling it names is a bit unprofessional. It may be a problematic device but using its real name would be a better way to discuss it.
Point made, I've had a "love" affair with Ikea firmware for almost 10 years now, sometimes it's a bit difficult to get over...
Again, thanks to @donkrell for discovering this workaround. It does indeed work and I now have nearly a dozen GRILLPLATS/spatzplat/BBQ Grill smart plugs directly participating in the C-8 Pro T's Thread network with no external dependencies after commissioning.
A step-by-step procedure with screen shots can be found here ..
It will be interesting to see long term if this device is a "one off" or if people start finding more and more devices that won't pair with the T hubs Bluetooth implementation. Hopefully it is the 1st case!
Well, I think IKEA in general tries to pigeon hole their stuff to weird implementations of the standards. Going back to their implementation of the TrafFri stuff (particularly remotes) that doesn't work well without the drivers that were reverse engineered to work around their issues.
Definitely would NOT surprise me if this was an "IKEA special" case.