Very interesting the pdf information is available here:

http://www.appliedmicro.com/MyAMCC/retrieveDocument/PowerPC/460GTx/PPC460GTx_PB4017.pdf

Nice chip, but I wouldn't call it SoC, because others include much more functions (for video, audio and I/O), and this only has ethernet, admittedly a lot of them and all very clever. Router chip, I'd say.

How hard is it to find a matching southbridge for these babies, in order to have the rest of functions demanded on a regular puter?

> Very interesting the pdf information

Not interesting at all for desktop purposes. See:

https://morph.zone/modules/newbb_plus/viewtopic.php?topic_id=6355&forum=3#64044

There are newer SoCs announced by Applied Micro that sport a PPC464FP core (i.e. with FPU) instead of PPC464 core (i.e. lacks FPU), but only reaching up to 1 GHz:

https://morph.zone/modules/newbb_plus/viewtopic.php?topic_id=6355&forum=3&post_id=72394#72394