The standalone pocket/handheld TV market is all but dead, and as far as I can tell it's as much to do with the switch to digital terrestrial.
There's a video on YouTube, "Whatever happened to handheld TVs?" that looks at a handheld television made by some no-name company designed for regular DVB-T (the terrestrial TV standard in Europe and some other parts of the world) and it's... less than impressive. It might simply be that the device is shite, but given my experience with other portable aerials, it's more likely that DVB-T just isn't suited to portable use.
That- along possibly with the need for decoding by low-powered devices- would explain why they created the separate DVB-H standard for handheld devices. However, that was around a decade ago and as far as I can tell, it never got past the trial stage in the UK, and flopped elsewhere.
Even if handheld digital TV had taken off, I suspect it's something that would have been integrated into smartphones by now, rather than being sold as a standalone device. As things are, most people are just going to watch "TV" over their phone's standard TCP/IP connection.