Although I don't own a Jornada 720 yet, I made this site to benefit those who own one.

About Puppy Linux on Jornada 720:

I found this attempt online:
http://www.murga-linux.com/puppy/viewtopic.php?t=28874&sid=b838496446ef84546b8c195356a70ef3

10 year old thread on HPCFactor about Puppy Linux: https://www.hpcfactor.com/forums/forums/thread-view.asp?tid=12389&start=1


Some related links (not Puppy Linux though) that might come useful:
http://darksnow.radiolivre.org/jornada/
http://drvarnick.tripod.com/
https://mifritscher.de/j720/
http://badaboum.bidibom.free.fr/linux-jornada-fs/
https://www.linux.org.ru/gallery/screenshots/9131353
http://www.h-i-r.net/2008/04/jlime-linux-wifi-scanning-new-userland.html

Might be interesting: Kernel 4.7 attempt on Jornada 720 (with progress):
https://www.spinics.net/lists/arm-kernel/msg524787.html

Jlime related:
http://www.wikiwand.com/en/Jlime