In what category this would go?
MEGA65 - (MOST PROBABLY) THE BEST COMPUTER
https://mega65.org

I have followed this for some years and it is quite awesome.

The category "not a phone" I guess.

Ok....
lets cut the crap here.
folks can get as asinine as they wish concerning what is FOSS and what isn't ...crying that they know better ..
or that they want a more delineated and comprehensive understanding of what FOSS is...and what it isn't....
And then ultimately making the whole debacle turn on its head , stating that EVERYTHING is FOSS to this degree or that...and then finish with a "So what is the point?" statement...
to refute and negate any others personal list of what they wish in their device or not.

Heard said tail-eating arguments before ....many times.

The blunt of it is ...
There is no mobile device that is FOSS ...
And if my logic is not flawed here Android isn't a "device" it is an operating system.
And....
No...Openmoko wasn't any more open or closed than any other OS....using the self same purported tail-eating logic that was applied....by said individual...

As far as "devices" go...
one will not find any completely FOSS devices....ever....
for one real world point...

The telephony aspect has to be closed source ...
Nations and Authorities would NEVER EVER EVER allow mobile devices not to be track-able, traceable.
That ultimately ...is the reason why one will never see a totally FOSS mobile device.

So from the dank little argumentative corner.... enough B.S. ...
Allow folks their definition of how much FOSS or how little a percentage they want in their device...with the full understanding that everyone else knows, it is a subjective and personal choice and desire....as to what their own criteria is.
And critics who wish to baffle gab the whole issue for the sake of just poking at things to stir them up pointlessly and needlessly ...
are not being intelligent or smart...
just transparent in their machinations.

Mega65 phnone has calling abilties so it seems to be a phone.

Thanks for not getting annoyed with me.
It wasn't my best moment, but I still think I'm essentially right...

I like that last definition, that is surely one thing that is very problematic with Android devices.
Another point - or possibly the same, in less technical terms: despite the OS being largely opensource, Android is made with a very different mindset and specifically designed to resist (benign) hacking and push its users into proprietary services. (good article on the topic)

One more point: While Android is Linux, it is not GNU/Linux. The term GNU did not make it into everyday usage like Linux did, but it's just as important. In other words, what people generally refer to as Linux has always been comprised of those two parts. GNU is not only the license, but also most of the software that runs on top of a Linux kernel and makes it an operating system. IMO and for example, Sailfish OS is GNU/Linux, while Android is not.

So, according to what you write you're really more interested in the operating system than the hardware itself.
Yet your roundup is about devices... this still confuses me.
So you list the hip scene devices and make clear what OS exactly they can run and what not?
I like how the list looks now, no doubt due to some recent edits.

Well, it is not exactly like that.
As far as "being a cellphone" or behaving like one is concerned it is not the authorities or nations or whatever that dictate that a device needs to be trackable and traceable, it is the nature of the cell network.

If a device needs to be able to connect to some provider network, be it of the GSM family (GSM, WCDMA, LT, 5G) or some CDMA-2000 derivative the device needs to register to a cell in the network with a persistent identity to be able to send and receive anything. This is a technical requirement and not a political choice; there also exists an open-source stack for 2G GSM communication and nothing prevents an able hacker to code an implementation for more advanced RANs.
TLDR; You can have open-source baseband implementation if you want to.

On the other hand the network was built this way for a reason, to be able to target billing correctly to the users and segment different services and service levels to paying customers.

If someone codes an open-source 5G baseband it has to operate by same rules as the closed-source implementations, or else the signalling just does not work; the TE needs to register to a cell with known identity or there is no communicetion. Period.

If there would have been a will to create an other kind of network that would enable anonymous and location-unaware communication between TE's, then the network would need to be designed differently. These design choices of the existing networks might well have been partly influenced by government agenda however more likely is that it was implemented the way it is done because that is simple and cost-efficient.