[chrisism]

Guys,
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 Yes, our google-fu seems to be about the same.  From the termux-am github repository:

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I haven't been able to find any official Android documentation of that fact though.  I also don't have an Oreo capable device, but I'd be interested to know if the Kodi builtin StartAndroidActivity still works in Oreo - I'm guessing it also wouldn't work.  If it actually does for some odd reason, one option would be to start retroarch with StartAndroidActivity, and then launch a game with similar commands as before (as some users said that works).

Another possible workaround would be to actually install termux-am and change the launch commands to use that.  It appears to be backward compatible with older versions of Android, so I'll install it and see if that may work. 

I was thinking about that too. Want to see what StartAndroidActivity does and been checking out the source code of kodi. But it is rather specific to using dataURIs as input, which isnt enough anyways.
As I said I tried the commands executed by AEL/Kodi directly in a terminal app on the Shield and it actually worked. So it might even be something that Kodi just needs more privilleges to actually execute it like this with the last Android update.
Keep us posted, I'll do the same.