What happens with a photon when it moves ouit of a galaxy into the 'infinity void', where there's nothing but 'darkness'? Does the photon decay in the end when there are no interactions?
In summary "no, why would it?"
If the universe continues to expand, then the photon will experience ongoing cosmological redshift, so it's wavelength (as measured by an observer moving with the general "flow" of galaxies in that part of the cosmos, will get longer, its energy lower, and it will, accordingly become more difficult to detect.
We can detect today photons emitted about 380 000 years after the big bang. At the time they were infrared light, but redshift has stretched them to microwave wavelengths today.