Sounds like quite the Rube Goldberg device.
I think I would recommend a DAP. I have a A&K SP3000. Very high quality output. But not for you… it may look like an iPhone but 3x thickness… but it feels like it is made out of lead… great for the table next to your chair.
But there are DAPs for all types of purposes. Many with very high fidelity… which I assume is what you are going for. Then maybe the right noise cancelling earbuds.
FYI. I have spent at least two decades traveling with portable head amps, cd players, high end ear buds, battery powered DACs… you name it. I have been carting around shoulder bags full of wires and Velcroed electronics with extra batteries since back in the 70’s.
This may be tangential or not. At the end of all these decades of hauling high resolution technology with me all over the world. I slowly realized that noisy environments would reduce resolution of what you could hear. It would reduce the treble, greatly increase the noise floor and give you a pretty lousy sound, unless all the racket stopped for a few minutes. In the end, I realized that for noisy environments the best thing is equipment with noise reduction and that has been equalized to sound good in that environment. So, for travel, I use Bose QuietComfort wireless headphones and my iPhone. The sound is punchy and really fun to listen to… the noise cancellation is outstanding. Having a “high end sound” in noisy environments is not that enjoyable… a different equalization works.
So, I would look at this as an opportunity to explore stuff made for your environment. Honestly, I walk and ride my bike for 3 hours a day with AirPod pros. They just get better and better. You might check out Bose wireless earbuds… I have not.