I think it might be theoretically possible, maybe (there’s bound to be caveats and gotchas, limitation of the platform); but the amount of time and effort required could also be an issue… Anyway, I would assume an application providing such an interface might be possible using one of the following “methods”:
Option 1: Humax provide the interface (seems unlikely for older kit).
Option 2: Someone works out how to “inject” all needed “calls” into the humaxtv process to do all the needed things (example: “play this file: path to file”).
Option 3a: “Dead reckoning” using the IR package injection method. LOL. Not that I could get the IR package to work on mine (I didn’t need it, so I have not tried to figure out why).
Option 3b: “Dead reckoning” using an external IR device. LOL.
Option 4: Parts of option 2 combined with 3 if the calls for option 2 could not be fully determined. For example: If you _can_ “call” into the humaxtv process to start playback of a given file, then an IR method can be used to pause, stop and so on.
I imagine option 3 could be “cranky” and slow in practice!
Notes on Alexa/assistants in general:
I don’t think the “dot” is very good at distinguishing between audio sources (for example: you and the TV) when the audio is not passed through it (that’s been my experience); it seems fine when streaming music thru the dot itself (which would make it easier to "cancel" that from the mic input). Another issue I have noted is that it occasionally picks up weird stuff from the TV audio.
Human: “Alexa, play the latest episode of doctor who”
Alexa: “Okay, playing later with jools holland”
Human: “Alexa, stop”
Nothing…
That’s a contrived example based on trying to get it to play specific tracks in my music “library”. The dot doesn’t seem to be 100% reliable when it has lots of choices… and sometimes when it doesn't...
Alexa: “I am having difficulty understanding at the moment” (we had no broadband for four days where I live; Alexa was non-functional, of course, the whole time – that’s a major flaw in all these big co. assistants: they only work if there is an internet connection). I did a test with an android phone without using the Internet a year (maybe more) back, it could recognize what I was saying; much of the logic for these assistance could be locally programmed (“turn on the bedroom light”), only going to the Internet for Internet things; that’s what I would want… if only I had the time...