It is NOT part of mainstream LDS doctrine or belief, to my knowledge. (Feel free to correct me, other LDS or former LDS folks, I don't know everything.)
Source: raised in The Church from birth to eighteen, most close family still members, live with two active members (my mum and a housemate).
The belief that each male member in the highest level of heaven becomes a God and gets his own universe to create and play in... that's real. The idea that Earth's god came from a certain star/star system... that's real. (If I could hie to Kolob in the twinkling of an eye... that's a hymn about where God came from.)
I have not dug deep into this case like many on here. I've watched the Netflix series. I have not, like a number of other cases, gone right back to the beginning of the threads and followed it all the way. I've been trying to focus on one big case at a time. I am on pause from Delphi right now, but up to about 100 threads in. I got up to date with Moscow after a couple of months. I'm currently reading Gannon. So, because I haven't read everything said here about this case, I do my best to give verification and context for mainstream LDS stuff, especially the stuff that is considered 'secret' or kept from newbies or outsiders. (Milk before meat, is what LDS say about that, talk about how nice it is that families stay together forever, don't talk about the other stuff until they've bought in.) But if there's something specific that this splinter group believed, the best I can probably do is say, yes, I've heard of that and it's part of LDS belief or doctrine, or no, that is not.
MOO