Can you link anywhere in the prime fiction where left or right hand path is mentioned please?
I also think you will find very developed storylines in both the Covenant and Khanid by doing their missions and interacting with their in-space agents.
The Covenant is not an alliance you can join. But there are things in the PF that do not exist in-game, like the Hematology Advancement Program, that we can create as loyalists to that faction/alliance.
Any capsuleer can do level one Blood Raider missions. As long as you do not kill more Blood Raiders, your standing will go up.
Che, most Blood Raiders are miners! There are level one through four Blood Raider distribution missions that require an insane amount of mining. Also, nine out of ten security storyline missions are actually distribution missions! There is only one storyline agent for the Covenant for all four levels and the mission is almost always "I need 6,000m3 Omber delivered to x, stat!". So mining Blood Raider is a thing.
Just go out and do the missions if you want to know more about a specific NPC faction, the content is all there.
There is no mention of the 'left hand, right hand' path in the prime fiction. It is something which exists in real life however.
Just because it is not mentioned, doesn't mean it does not exist. Monasteries are not mentioned specifically by name in the prime fiction either, but EVE does have religious orders and Nuns.
Mysticism isn't mentioned specifically by name either, but a school of mystic thought is mentioned in the PF.
I first learned about the 'left hand path' to enlightenment from seeing a documentary about Aliester Crowley. (It might even be a concept he made up himself). Indulgence instead of abstinence, vengeance instead of tolerance, and so on.
Whether or not you choose to use the word or concept, I think it is a fitting analogy. There are two equally valid paths which lead to the same destination.
At one time school children were taught that the use of the left hand was forbidden. In Latin, the word for left hand is
sinistere. In reality of course, there isn't much difference between using your left hand over your right hand, and in some cases being a lefty gives you an advantage (like baseball).
In order to find God, the Priests would tell the congregation that only the right hand path was acceptable. Starve, suffer, flagellate yourself, prostrate and humiliate yourself, and so on.
However, historically the Catholic priests and Popes (such as the Borgias) sometimes did the exact opposite of what they told their parish to do. The people starved, toiled and suffered while the Priests ate lavishly, accumulated wealth, had orgies and so on. 'Do as I say and not as I do.'
Somehow, these priests and the nobility were able to commit these abhorrent acts and still convince themselves that they were going to Heaven. One explanation is that God has created everything, both good and evil. The only way to understand God wholly though is therefore through both good and evil acts.
Aestheticism (also not mentioned by name in the PF), means denial, repression, poverty, meditation, etc. This is the 'right hand path' which is the most acceptable, traditional, and does lead to God.
Indulgence, such as the lavish orgies of the Bad Popes such as the Borgias, is not a 'sin' or 'heresy' (because the Pope says so). Instead, it would be called the 'left hand path' to God which only a few people are capable of.