I'm no expert, but I've come across "third positionism" and other forms of "left fascism" a fair few times over the years.
The first point must be something of a caveat. Just like the left much of the stuff you encounter is just noise endlessly spewed by a handful of egotists and hobbyists. Much like the above mentioned TS. A few individuals with a lifelong enthusiasm can generate an awful lot of apparent publications, organisations and websites. That's not to say this stuff doesn't have a genuine presence, it does, but that one should sift carefully.
Secondly, it's not "new". You can pick all kindsa start points, but old namesx like Strasser, Evola and Chesterton are regularly invoked.
I guess much like lefties exploring non-Leninist communism, much of this is non-Hitlerite fascism with a similar sort of purist appeal.
In the Uk they've explored environmentalism and animal rights, welsh and Irish Republicanism too.
Some get all into catholic fundamentalism.
Others went out and got hurt in the Balkan wars. I forget which side they fought for.
In Italy there's the whole Casa Pound thing, but it's complicated out there. Fascism ain't a fringe pursuit like here.
I've even seen Mexicans pushing this stuff.
However, it's also worth bearing in mind that aside from true believers, much of their audience and more casual activists are (again just like the left) hopping from vehicle to vehicle without any real preference.
For example, we "acquired" a large bunch of things from a local fash, he happily mixed his third positionist tat with with more trad NS paraphernalia.
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Apologies for the rambling nature of this post...
