I know the phone is old, but I still have one and my kids have one each. However, they are still playing the 0.8 version because I don't want to replace fully functional devices just because MCPE controls has stopped working

The part where controls aren't working is nothing new, it has been around since 0.9. But at least the game always worked fine. This has been reported several times (just search older Jira cases), but to summarize: only D-pad working, no other buttons or "sticks" works or can be assigned.

New from 0.12 (I think) and still applies, is that the game doesn't work at all. It can start, generate a world, but as soon as I start to move around, the game will hang and after a while make the phone crash totally.

Here's a video on YouTube of how it looks:
https://www.youtube.com/watch?v=Bafi5QkGNI4
Here's the reddit post for this video:
https://www.reddit.com/r/MCPE/comments/3rhcfr/this_is_how_broken_mcpe_is_on_xperia_play_100/

This is an older reddit post regarding the controls:
https://www.reddit.com/r/MCPE/comments/2sx5dv/the_xperia_play_situation/

I don't know if Nvidia shield supports MCPE these days, but I can't think of another device that would benefit from built-in controller support and can be comparable. I guess that's why this issue has been ignored. However, on the positive side, today I noticed that the auto-jump feature can be turned off, happy to see it, totally missed when it was implemented! (However, it didn't work in the short test I did before phone crashed...)