If these are really important for you, just stay with the Apple Watch. I don't think they'll improve the audio quality etc. to da big degree.
For me, I won't understand the sound quality difference of Sennheiser Orpheus and a cheepo earbuds on my ears, as there are many more noises like wind, friction of cables, my breathing and jumping, bumping on the road while running.
I'll bite although I'm not sure you are that serious.
Audio has been a problem with the Fenix 6, in fact, probably my biggest gripe with my 6X. Wear the watch on my right wrist, sure thing Garmin. But I never really experienced the rasp, it would just drop the signal and take a break.
As far as the smarts go, well, yeah, it's not even a contest. It's like playing chess without a queen, rooks or bishops. Had they included Siri, for me at least, it would have gone a long way.
The data side is better on the Garmin, although not hugely so, and if you have integrated equipment, power meters, Stryd, HRM, etc., it does integrate better with Garmin than the AW. On the other hand, you won't need all of it on the AW side either.
Garmin wins on battery life, but for anything besides very long hikes, runs, you can just buy a second AW and you'll always have a full charge. And 2 non cell AW's are the same as 16GB Garmin on an Epix, and many of the Fenix's.
Personally, I am keeping both Epix 2 and my Apple Watch Series 6 cellular. For one reason only- being reachable and contacting someone in the event of an emergency and streaming music/podcasts.
