I have two remotes: one for my TV, and one for my AV receiver. I realized I generally only need four buttons: the power button on each, and volume up and down on the AV receiver remote. Arguably that could be compressed to three; I very rarely want the AV receiver on and TV off, or vice versa (unfortunately neither remote supports programming it for the other device, so I can't use the "system on/off" functionality).

So for my regular use, I wouldn't mind voice control for this, though voice assistants have trouble hearing you when there's extraneous loud noise, so volume control (especially when a really loud scene comes up and I want to lower it) would be difficult.

I don't like the idea of a smartphone app, because there's the hassle of unlocking my phone and finding/switching to the right app.

The author also mentions using gestures, which also seems very error-prone.

So I guess a dedicated remote control is the way to go, though I wouldn't mind having a single bare-bones power+volume remote, so I could toss the full-featured remotes into a drawer and only pull them out when (rarely) necessary.