Hi thanks for reading! Regarding Doppler shift, it literally leads to the addition of expansion of space and dark energy; this makes it a complex interpretation rather than a simple one. There is no consideration of Occam's Razor in adding such concepts to the fundamentals of reality.
The most important aspects of the redshift observations are a generally linear relationship of redshift per distance (Hubble's Law) and an accelerating rate of redshift per distance. These can be explained by gravitational redshift as a result of light traveling in Figure-8 orbitals due to an object so massive that it bends all light in the observable universe. So as it travels through this Figure-8 orbital repetitively it additively arises at higher and higher redshifts per distance.
Additionally, there is not a perfect fit of redshift per distance which is actually rather detrimental to the expansion of space interpretation, but this makes perfect sense in the gravitational redshift model because it depends on the galaxy's actual positioning and the angle of travel of the light initially with regard to this object causing all light to be gravitationally lensed in a Figure-8 orbital. If the angle the light travels to arrive at Earth requires it to move initially towards the object, then the first portion before it begins to flow in a Figure-8 orbital would be only blueshifted before it then additively is redshifted as it travels in this Figure-8 pattern. Or alternatively the angle could be directly away from the object so it has more redshift in the first portion than in the previous case, so this discrepancy would lead to a rather wide range of redshift per distance, which is much more in line with what we see than some general uniform expansion of space which would be much more tightly packed data points.
Also, non-trivially, this Figure-8 orbital of light on the large-scale is very significant because it actually explains how gravity causes electromagnetism. An electromagnetic field is caused by the force of gravity pulling infinitesimal particles into Figure-8 orbitals through its center of gravity (like neutrinos passing through the Earth), the summation of these particles flowing in this way being then observed as the electromagnetic field. Thereby, gravity causes electromagnetism. The mere fact that gravity can be used to explain electromagnetism, which is considered causeless, demonstrates that this is actually what is happening. Notably, this matches Occam's Razor because it reduces the fundamentals rather than adding more concepts that all work together, thereby simplifying the model. All things are caused by gravity.