Calling the O9A "neo-nazis" is lazy and inaccurate, given that neo-nazi groups hate their guts and ban their members at the first whiff of 'Traditional Satanism'. Just take a look at the threads on Stormfront regarding them and it should be clear how they're viewed by those groups. They are neither welcomed, nor appreciated and are considered to be making the far-right look bad.
Most, if not all of the current groups claiming to be O9A are full of shit and consist of a bunch of kids; online edgelords who want to make themselves look dangerous, but who never actually seem to follow through with any actions beyond posting pics of themselves on social media.
I've studied the O9A for over a decade and they most certainly haven't "died out". The fact we're talking about them in 2020 confirms that their memeplex has been successfully propagated, which was essentially the purpose of their second iteration (1986-2009). If the official line from Anton Long/David Myatt et al, is to be believed, post-2009 the O9A isn't even technically a satanic group anymore, having moved to the worship of Baphomet as archetypcal feminine.
Beyond the glamours and abstractions, there's a coherent system involved that has its roots in Greco-Roman hermeticism, alchemy and pre-Kabbalistic models.
"Hope not Hate" are a propaganda outlet, but they've got the ear of the media and government. This gives them more clout to throw around accusations without evidence. For all their claims of being about 'hope', they're a hateful bunch who actively try to ruin people over nothing more than the thoughts in their head. The ACLU and SPLC in the US are the same, and I wouldn't trust a single one of them.