I didn't think they have these versions. I didn't even know PCMCIA cards existed for the PS2.
I tried looking around and it's freakin' rare. Damn, this console got some cool accessories I didn't know existed.
Well, they are Japanese exclusives (like the whole 1xxxx series - outside of the equivalent DEX models)
They probably changed to internal HDD since: the only retail card made was the ethernet+hdd one, early PS2s had a two-part motherboard that likely occupied the HDD rail space, less fragility than an extra disk box with a short 30+ pin cable, and of course $ony's general attitude towards cost cutting and respect of consumers' investment into a platform
I wish there were some sort of [...] you could install that will at least give you USB 2.0
Now there is - the PS2USB - but it's only made in Expansion Bay format!
(It's probably the first original 3rd party product for that socket; but as an original device needing its own drivers, compatibility with homebrew is much lower than other options - it was originally only designed for a license-violating fork of OPL, though it now supports Popstarter and SMS at least - and long term support is very questionable according to the inventor's own words)
(Same guy invented the PS2NetBox, a PS2-specific SATA/IDE to Ethernet external drive, which despite the same criticisms at least fills a rather large niche of many PS2 Slim users; but PS2USB is much less useful when an original Sony network adapter + express shipping from the USA is cheaper, widely supported in homebrew, and doesn't have an external drive sticking out)
I wish there were some sort of modchip you could install that will at least give you HDD connection.
HD Pro, but due to how it's implemented it's not much faster than USB 1, and support is even less than the above products (it adds an 8-bit, non-DMA interface on the data lines used for the firmware rom!)
I'm not even sure if the Modbo (which is a Matrix clone) supports the 1xxxx series...