It's been years and it seems there has been little advancement in this space re: wireless hard drives.
I was looking for something which I could take on a long trip around the world, preferably could be charged via Micro USB, USB3, can support internet pass through (i.e. the drive can connect to the internet independently and then share that connection), decent iOS apps, and preferably x265 support for streaming to a tablet (looks like I'd need DLNA for this). Seems like there's nothing quite like this out there yet.
So far the best option seems to be the cheap Seagate 500gb wireless drive >
https://www.hachi.tech/product/0763649066812/Seagate-Wireless-500GB-Green
It can be charged over Micro USB (ie my battery pack) but it doesn't support DLNA/acting as a streaming device, nor does it support USB3. Hmm. I also doubt x265 will work either.