It would be a struggle to replace the original though you might still find one somewhere.
I would consider a gopro or gopro clone stuck or attached under it, video would be messy while moving without a gimbal, but stills from it would be quite good.
You won't be able to see what it can see live though.
If the link to app otherwise works you might still get info about remaining battery and other info such as which way it's pointing at least.

The P3 series is a big leap forward in every way and worth looking for a used one in good order if you are getting into it - and don't mind the size over more recent models.