"Satanic neo-Nazi" is an oxymoron, as Satanism is anti-collectivist. The O9A is a meme that has been around for decades. It has no membership or consistent literature, anyone online can come up with the most extreme and “evil” writing and claim to be O9A. https://www.thedailybeast.com/us-army-soldier-plotted-mass-casualty-attack-on-his-own-unit-with-satanic-neo-nazi-group-feds-say

It’s been long understood in the “occult” community that the “O9A” is just bait for FBI agents trying to catch deranged idiots attracted to “extreme” nonsense. That’s what this turned out to be, as this whole operation was monitored by an informant. https://www.justice.gov/usao-sdny/press-release/file/1287701/download

It's basically Slenderman for angry teenagers & edgy artists. A "sinister" meme to see who can sound scarier. But “Solider provides information to 12 year olds on Discord” doesn’t sound as good.