D810/D810A questions

I'm getting a D810 in a few days. Some repair work needed, truly nothing I can't handle.

I'm an experienced D800 user.

Some D810/D810A questions come to mind, though.

I do have a fair interest in astronomy.

I generally understand what the A version offers vs. the D810.

Is it possible to get a D810 converted to D810A specs? If so, where?

How does a D810A differ in terms of what your photos look like, vs. a D810 when you use the D810A
as a regular daylight camera, outside of its astronomy specialty?

Dont know if you could find it but i think there was a very brief explanation on Nikon Rumors when the A was launched,first they said it would be a great camera for normal subjects then a bit later they explained why it wouldn't.

That explains it well enough. Thank you.