Depends on how your warlocks feels about things.
Kyrian’s big identity, or rather identity crisis, is the conflict between their tradition of giving up on the memories of their mortal lives, to be truly impartial when carrying out their duties of ferrying mortals to the Shadowlands. Their traditions dictate memories and attachments to the mortal world are harmful, and only serve to distract you, to make your job harder. But now, many have rejected that notion, and are fighting for the exact opposite - the embrace those attachments and memories, believing the Path is flawed and they can utilize those attachments and memories - pain, grief, love, longing, loss etc. to be better, rather than reject them entirely to be “effective”.
Void elves struggle with their new void-suffused state of being. They require an iron will and a constant effort to keep the whispers down and ensure they are the ones who remain in control. Perhaps one might fight the kyrian’s practices useful - maybe giving up on your emotional attachments and old life helps a void elf reach a state of harmony where they can better control the void - where the void’s taunts and threats, its mindgames and maddening tactics no longer work because of the lack of levarage.
Or maybe they think the Kyrian are flawed, and agree with the push for a reform, for embracing and coming to terms with one’s feelings and past to better understand their present. Maybe exactly those attachments to their mortal lives, to their loved ones, the losses they’ve suffered - are why they’re able to emerge victorious over the void every new day, and despise the thought of others having to give what in their opinion is the truest strength one can harness.
As for classes, every class can more or less fit everywhere, and the covenants don’t have out mortal prejudices. Warlocks simply utilize chaotic fel energies, a fundamental part of the universe. They’re not any more evil than a priest harnessing the light, or a mage harnessing the arcane - which has proven to be just as if not more corrupting.
If you simply want a fitting aesthetic, I would recommend venthyr - which is where I personally wish to bring my Void elf priest. Of course, you might not like the warlock’s poor ability there, but kyrian isn’t exceptional either, and aesthetics and lore should always take precedence.