Haha I did the exact same thing. Looks gorgeous and makes the colors on the TV look more crisp(?).. Tho it's propably more of a placebo effect. My 4k set is on the cheap side of things though. I have a 58" Samsung TV with HDR10, but max luminescence is only 1000 knits. So most HDR games, while looking better than SDR, are not that "omg wow" unfortunately. But I must admit that some games that I played or replayed on my X surprised me, with what my TV is capable of. I think Gears 4 is one of the best looking games on the machine. It's kinda magical.
In regards of my sound setup, I barely use my TV speakers or my Soundbar. If I'm honest, my soundbar is back in the box because the wiring looked stupid. For gaming I exclusively use my Turtle Beach Ear Force X41 on Xbox. It's getting on the older side of hardware but it still does a fantastic job. How is that Dolby App for the fake atmos on headphones?
I only used headphones for like an hour, but not enough to think more than - "that's cool!" I think you'd need more scientific feedback, but I did find the weird licensing thing to be surprising, rather than offputting and the two experiences were back to back. So it probably poisoned me a little. But I could hear it, for sure. And the App doesn't do much beyond "permit" and enable the tech on my setup. I assume the mobile version does more - Bose's connect app for example is weirdly useful if you connect multiple devices to the headphones.