Nice!
Jornada 520 is a Pocket PC device, running Pocket PC on SH3.
I think a lot of sites like Handango, Pocket Gear are gone so it's hard to get apps these days compared to ~15 years ago.
One place is:
Mobyware
http://www.mobyware.org/pocket-pc-os
You can still download old Pocket PC apps, maybe give it a try?
I liked using Leo's Flight Simulator on Sigmarion 3, it was amazing back in those days...
I enjoyed Kittpeak's Racing Days, which the site still exists:
http://www.kittpeak.co.jp/racingdays/index_e.html
It was like a Pocket PC version of Gran Turismo and Need For Speed combined.