Sorry to bump such an old post, but it solves problems.
I have been using a CyberPower H420MP with a couple of AA batteries on the road with the original Pandora for years (rare solution so they're expensive):
And the CyberPower fits nicely in the original Pandora carry case.
I also use my favorite Kensington Orbit wireless trackball with the CyberPower:
And I keep the trackball in a nice mobile carry case:
The CyberPower allows me USB memory sticks at the same time as the trackball, as well.
From the necessity of work I just had to order a solution that includes ethernet - although I haven't tried it, yet. The only currently available solution I could find that had Ethernet, USB 2.0 ports, and allowed external power supply, was:
UPDATE : UGreen RJ45 Ethernet Adapter & USB Hub works great. I'm using USB power cord listed above plugged into a power-strip with USB ports on it to power the UGreen Hub. The Pandora is actually powered off the UGreen Hub and the Kensington trackball is working off the UGreen Hub as well. Ethernet works great - only feels a little faster than wireless - probably because the Pandora is just that slow.