Q:

My name is akin to my size

My name is akin to my size
  Each can be complex or concise
  I remain within gaze
  In front of your face
  Observable under the right eyes  
My true prefix is one of a kind
  My infixes are aplenty you'll find
  Even if one knew
  What they attempt to construe
  It would take them a very long time  
Considering freedom and span
  I am not a favourable fan
  Yet I still do support you
  Will continue to guide you
  Hold heavy loads as much as I can  
In multiple forms I exist
  In strenuous times I assist
  With so much potential
  I am quintessential

Attempt to unveil me, I insist!
Hint:

 I am organic in nature.

Hint:

 I am a specific substance.

Hint:

 I am named after a god.

Hint:

 I am a macromolecule.

Hint:

 I lie beneath the skin.

A:

I wonder if you might be a:

 MEDIUM

My name is akin to my size

 Medium is a word that can describe the magnitude or size of some property (e.g. a steak can be cooked 'medium rare', a T-shirt can be 'medium size'...).

Each can be complex or concise

 A 'complex medium' is a form of growth medium which is used in a laboratory for culturing bacteria. With regards to 'concise', this might be inferred as a synonym for 'compact' - a compact disk (CD) is a form of storage medium...

I remain within gaze
In front of your face
Observable under the right eyes

 In the case of a growth medium, bacteria will culture within it 'right before your eyes', but can only be seen (or observed) using the right eyes, i.e. a microscope.

In multiple forms I exist
In strenuous times I assist

 There are other meanings to the word 'medium', one of which is a person who acts as a conduit for the voices of the dead, or a way to connect to 'the other side'. In such 'strenuous times' as shortly after the death of a loved one, somebody may attempt to communicate with their dearly departed through the use of such a medium.

With so much potential
I am quintessential
Attempt to unveil me, I insist!

 These lines simply refer to the word 'medium' having multiple meanings, although the use of 'unveil' here further conjures up the image of the heavily curtained (veiled) and perfumed room usually used in the work of a talking-to-the-dead medium...

A:

I think the answer might be

 Microbe (or even microorganism)

My name is akin to my size

 The name contains "micro" which indicates its size.

Each can be complex or concise

 These organisms can vary vastly in complexity depending on the size of the genome.

I remain within gaze
In front of your face
Observable under the right eyes

 Microbes are present everywhere but can often only be viewed using a microscope

Considering freedom and span
I am not a favourable fan  

 Bacteria and viruses are often seen in a bad light.

Yet I still do support you
Will continue to guide you
Hold heavy loads as much as I can

 Microorganisms often help with bodily function and to protect the human body.

In multiple forms I exist
In strenuous times I assist  

 There are many, many forms of microorganism which provide a vast array of functions.

With so much potential
I am quintessential

A:

I think you are:

 Eyeglasses

Verse 1:

My name is akin to my size
  Each can be complex or concise
  I remain within gaze
  In front of your face
  Observable under the right eyes

Explanation:

 "Eyeglasses" are akin to their size in that they contain the word "eye" and are the right size for your eyes. Other kinds of "glasses" (eg drinking glasses) could be any size. Prescriptions vary, meaning the lens can be "complex" or "simple" (concise). They are literally right in front of your gaze, but only under the "right" eyes (of those who require them).

Verse 2:

In multiple forms I exist
  In strenuous times I assist
  With so much potential
  I am quintessential
  Attempt to unveil me, I insist!  

Explanation:

 Glasses are available in many forms (spectacles, monacles, pince-nez, contact lenses etc). They assist with eye strain and are essential to those who need them. "Unveil" means to allow something to be viewed, and eyeglasses help you to see things which otherwise you could not.

