memes

No my dude, tonality characteristics are about how each driver responds to each frequency signal. There's tons of research that goes into the materials and construction of headphone drivers, they're not all the same. Soundstage is also not subjective. Although I do not know how you can measure it, I've played audio through my open headphones to people and they genuinely cannot tell if the sound of an opening door for example is coming from the headphones or if it's real. That's the type of efect soundstage gives you.

So you've only tried a very siblant headphone (dt880) which isn't necessarily bad and a JBL wireless headset? Instead of reading so many forum posts, go to an audio shop and try the actual headphones before trying to lecture other people in things you have never experienced yourself. I'm sorry if it sounds harsh but you're trying to give advice on something you've never tried and have only read random forum posts about.

As I said there are plenty of audiophiles whose “lived experience” is that $2000 golden cables are necessary and that they can tell the difference between any $200 and $1000 DAC (even though a decent DAC in that price range already has a dynamic range and signal-to-noise ratio of 100-120dB which should be totally indistinguishable from perfectly clear audio for all humans

I am not one of those people. Even though there is snake oil in the industry, that does not mean that everything is snake oil. If a cable passes the continuity test then that's good enough. And regarding dacs, a lot of the advice I've read also says that going beyond $100 you won't find a big difference in sound.

Usability is kind of secondary

Usability, my friend, is king. When you get older and have to do tons of stuff, adding more things to the list ends up getting very annoying. Not just that, if you were to migrate to iOS for whatever reason, you'd lose the ability to eq your headphones. So an app existing and being maintained today and for 1 mobile os does not guarantee that the problem has been solved forever. You're depending on a random third party.