The Netwalker was officially sold by Zaurus on the japanese market only, it was imported to the rest of the world only via the grey market, so I believe that most of the activity was on japanese forums, which of course is of no use unless you have a good enough knowledge of the language...
About the alternatives to a Netwalker, a couple of people here have bought a new GPD clamshell, which is even smaller:
https://www.oesf.org/forum/index.php?showtopic=34424On the plus side, it is available now, it's a new device with good specs, it has an Atom CPU which means that x64 Linux distros and programs should run on it with only minor tweaks required, hence Sunvox should run too. On the other side, officially it runs only Windows 10 and it is still not known how well will Linux run on it, plus the Atom CPU has been discontinued by Intel and sooner or later they'll stop producing them, so the GPD Win will be discontinued as well. If you don't mind running Sunvox under Windows though, you can probably have it already running from the start.
Varti