what's the issue here? if you buy large headphones from the same company you buy the your phone from, in a future where fairphone no longer exists (which playing the odds, is likely) at some point your also no-longer-supported phone (which functionally becomes slower every year because mobile application hardware requirements appear to double every year) might advance to support new fancy bluetooth things your headphones don't support?
I honestly (not hyperbolicly) don't see how a phone not having a 3.5mm jack is relevant to the headphones _having_ a 3.5mm jack
If the headphones are meant to be used with the phone, then the idea that the headphones are future-proofed because they have a 3.5mm jack is pretty meaningless if you can't connect them to the phone with that jack.
In 2023, most people who give two shits about running wired headphones are using a USB DAC, even if their phone has a 3.5mm socket as the onboard AD/DA chipset is usually mediocre and struggles to drive most high-end cans.
The only person that I've ever seen do that had to replace his USB socket after a few months. It turns out that USB C is not designed for long term constant torque being applied, as is the case when it has a dongle attached constantly in a pocket bouncing around. Perhaps if someone sold a dongle that sits flush with the device, and is secured such that no force is transferred to the socket, that would help.
The dongle solution seems to only be good for sitting at a desk. Not for a device that is literally called "a mobile".
I honestly (not hyperbolicly) don't see how a phone not having a 3.5mm jack is relevant to the headphones _having_ a 3.5mm jack