The free market is allowing a company like this one to exist because they're banking on there being enough people that care about this sort of thing to buy into their device rather than buying from a well established brand. That assumption will be put to the test very soon and advocates for this sort of device have a great opportunity to do so. The bitter reality though is that there might be a market large enough to sustain a company like this, but it won't make any big waves in the industry as a whole. Because people generally don't care.
> Seems I have less and less choices in that department these days, especially at the flagship tier
You're making a conscious decision about what sort of compromises you're willing to make with regards to your devices, just as everyone else is that buys electronic devices. There are plenty of phones with headphone jacks that have premium hardware specs. Sure, Apple doesn't have it. Samsung doesn't. But plenty of other manufacturers do, and people aren't buying them. Sony's top of the line smart phones have a headphone jack. LG's Vx0 line had headphone jacks and a fancy DAC built into them. ASUS's RoG phones have a headphone jack too. There's plenty of choice if it's actually that important to you. Buy those devices and hope that you can convince enough other people that the feature is as important to them as it is to you.
You don't need to shit on other people's choices nor assume that they aren't informed about the choices they make to want for the things that you do.