This is just a guess, but both those apps list 'access to GPS' as one of the permissions they need. Looking around google play it seems that apps that want access to GPS tend to be listed as incompatible (not surprising, the PRS-T1 has no GPS receiver). I can't guarantee that all are listed as incompatible, but I haven't found one yet that is compatible...
You could try to get the .apk files outside of google play to see if they will install that way. But to be honest I'm not sure how likely that is to work.