I have a set of 18 year old Shure SE530 headphones that I still use. I simply bought an external bluetooth adapter for them. I would challenge anyone to do a double blind test with them bluetooth vs. hardwired.
Was going to post this. I didn't want to give up the quality of my IEM's so went with a BTRK3 adapter and feel like I have the best of both worlds. Bonus is I can play mobile shooters with 4 fingers and not have a jack in my way.
My problem with that solution is that it's yet another thing to carry and isn't feasible for situations like listening to music while running. I tried the UTWS5's but they literally couldn't maintain an uninterrupted signal while walking with the phone in my pocket.
I really hope a good wearable true wireless solution pans out for IEMs or I'm going to have to permanently abandon the format.
This is basically the route I took, albeit with a BTR5 and SRH840s, and I don't think I want to go back. I can slap that little shit on whatever I want and it'll make the sound quality orders of magnitude better.
Edit to add that I recently got 250 ohm DT770s and they work great with the BTR5 as well.