It may be hard to determine "gray" Jedi in current canon, because the reality has become more about "grey" force-users in terms of what George Lucas set up between a Jedi and a Sith (or the light and a dark side) in the preview of the Original Trilogy, which he then began to contest in the prequels.
But since Disney's acquisition, it's currently being furthered in comics (Doctor Aphra, Darth Vader 2017+), books, tv series (Star Wars Rebels), and within the narrative of the Sequel Trilogy (The Last Jedi) to better examine notions of philosophy, applied methodology, and purpose/goal of said philosophy, especially where the Jedi's perspective is concerned...
A Couple examples of gray Jedi:
OBI-WAN: Don't defy the council, Master, not again!
QUI-GON JINN: I will do what I must, Obi-WanQ
Qui-Gon Jinn introduced and showcased in The Phantom Menace, had philosophical problems with the main stream Jedi of the Republic Era in terms of their hierarchy practices with the Jedi Council, which one could argue was pushed further still by a loyalty to the Republic itself, as being one of several factors leading to their fall along with Qui-gon bringing Anakin Skywalker into the preview of the Jedi Order. In episode I, Yoda is the one to initially deny Anakin's training after Qui-Gon seeks their approval, even though he states he will do so without if he must. At the end of the film, Yoda changes his mind. Then during Episode II, Yoda whose tune is quite different, tells a doubtful Obi-Wan that sometimes the older more experienced Jedi forget themselves, which is followed through with the younglings finding the solution to Obi-Wan's lost star/planet.
It should also be noted that Qui-Gon's former Master left the Jedi Order to become "Count Dukoo" and eventually a Sith apprentice Darth Tyrannis. This is important because it represents a transition between the dark and the light, reflecting Anakin's own turn and presenting "Byronic Heroes"
Another more recently introduced into canon during the Doctor Aphra and Star Wars comic crossover event: The Screaming Citadel, is an offshoot sect of the Jedi called, Ordu Aspectu.
According to one account, supported by the father of the archaeologist
Aphra, the Ordu Aspectu was a violence-loathing Jedi sect that sought
to selflessly prolong life for all. When the orthodox Jedi raided
their fortress, the Ordu Aspectu were forced to activate a device that
seemingly caused them to disappear, perhaps ascending to a higher form
of existence. However, according to the younger Aphra, another version
of probable events was that the Ordu Aspectu had kidnapped Jedi
Padawan learners, whom they callously sacrificed in an attempt to gain
the immortality they sought. Aphra also stated that the Ordu Aspectu
might not have existed at all, and the term might simply have been an
argument between Jedi grammarians of more recent years.
Doctor Aphra gives Luke two accounts of Ordu Aspectu's practices, her fathers, which pegs the Jedi as extreme "purist" in comparison of the mainstream Jedi, but another interpretation suggests they were closer to Sith by being willing sacrifice Jedi Padawans for to try and reach immortality, but Aphra also comments that perhaps they didn't exist at all and rather there is some argument within the historic account of whom the Jedi were once...
The comic also subtly shows an instance where these Jedi may have been somewhat false Jedi, because Rhur's ability to immortalize himself by using some kind of holographic-projecting crystal comes off like a fake force ghost, which may lead one to the new mythology and philosophy exhibited in the The Last Jedi...
The Saga Force Narrative & The Sequel Trilogy
KYLO REN: The past must die, kill it if you have to.
LUKE SKYWALKER: I only know one truth: It's time for the Jedi to end.
It was established prior to The Force Awakens that Kylo Ren and Supreme Leader Snoke do not view themselves as Sith, but as it currently stands viewers do not understand either's philosophy outside of Snoke believing in the power of the Skywalker bloodline (Aftermath trilogy, The Last Jedi) and Kylo Ren believing he needs to finish what Darth Vader started (but what is that, exactly?). Let alone where The Knights of Ren stand.
During the course of The Last Jedi viewers come to understand that one reason Ben Solo became Kylo Ren and aligned with Snoke was out of Luke's fears of Ben's darkness, when he nearly makes an attempt on his life. Despite that he catches himself, Kylo witnesses him in the process, in which Ben then turns around and kills the rest of the apprentices at Luke's school. Both of these actions call back to Anakin's betrayal and fall to the dark side (Attack of the Clones, Revenge of the Sith). Luke then vows never to teach again...
SNOKE: The darkness rises and the light to meet it.
It's in these moments that we see the "gray" lines are not just within the struggle of the light and dark itself, but also that the struggle, on the Jedi side of it, is that Luke seemingly didn't evolve the Jedi philosophy from the time of Yoda, in which one may presume is one major cause of his failure with Ben Solo (but there are other factors too, such as Snoke's influence on Liea's womb paralleling a new more official reveal of Sidious' creation of Anakin).
LUKE SKYWALKER: I will not be the last Jedi
A lot of evidence of some kind of evolution or revolution as the result of this story, comes in the form of Rey: a character that is in a savior role. She is not only able to get Luke to train her, but to remind him of his better self that he once was, which causes him to sacrifice himself for the sake of the future of his family and friends (Leia,The Resistance). This is then furthered by Luke's ability to astral project himself and interact with living beings (his sister), Yoda's force ghost evolving to interact with his environment more directly, the Jedi text mysteriously turning up on the Millennium Falcon, and the legendary of Luke's sacrifice sparks 'a new hope' in the galaxy.
So at any rate it seems the end of the Saga story is in affect about some kind of force cycle cosmology story, where the Jedi's viewpoint of The Force needs to evolve, possibly become more "gray" in order to be maintain the light side, as it were, as opposed there being gray Jedi already in existence as an organized group (or Sith, of something like the Bendu)