Indian (South Asian) lad here, I don't know most of the references, but I came across some clues while researching. All of this is with reference to the USA.
Boymoder is basically a "he", who's transitioned to a "she", but is pretending to be a "he" again, by wearing baggy clothes and cutting hair.
Sweet tea is a Southern state specialty?
Plantation is a slavery reference - black slaves were transported from Africa and made to work in inhumane conditions. USA has a still-active, 200 year old separatist movement - the flag you see behind resembles the confederates - but it's theme was modified to make it similar to the trans flag. The confederates are the Southern (South and South Eastern, to be exact) states that wanted to keep slavery, so they were willing to break away. There was also a civil war back then. The confederate states are also called red states in general, I guess? But red states are where Republicans are voted, so that is probably an incorrect definition.
Yankee is probably a Dutch derogatory word for American of British ethnicity, something about calling them pirates or vagabond, I don't know.
Blahaj is a shark plushie sold by Ikea, also popular within the American trans community for reasons unknown.
Dixie, more precisely Dixieland is probably a derogatory word for southern states. Dixie is also an anthem for the confederate states?
Dixie blahaj probably means a dixie-themed blahaj, and yankee blahaj means similar stuff for the yankee one. Kind of like how communist-themed blahaj will have the sickle and hammer, and the Russian fur-hat with a star on it.
Anon's fantasy is about a timeline where the civil war has happened during the present times. With technology as well as bonded slavery.
The rest of it is multiple sexual fantasies about:
getting non-consensually snu-snued by the soldiers and being treated like a objectified woman, while pretending to be ignorant about them being trans - almost as if they pass like a real woman
the act of them torturing anon to get out of their tomboyish behavior and to behave more like a stereotypical submissive conservative girl
all the soldiers declaring them as their wife - something about polyandry
more aggressive, unsafe snu-snu (that's what the word breed means in urban dictionary) and more weird sexual fetish, because Anon insulted the Union soldiers
As an American, you just gave a better context for the stuff I did understand than most Americans could.
The colors weren't red and blue back then, they were Navy Blue (North) and Grey (South). While it's true that most of the south was predominantly Democrat back then, the events leading up to and including the Southern Strategy in the mid to late 20th century, cause the Republicans to stop being the progressive party, and become the fascist party. The Democrat didn't really move much to the left during that whole mess. That is why you'll see the southern states being referred to as red states today, because they are gerrymandered to guarantee Republican victories.
I did some googling and it seems like "yankee" and "dixie" were nicknames of the sides in the American civil war. A plush IKEA shark is involved somehow too.
the states that won the civil war are more likely to accept trans people for who they are, and are more sex positive, than the states that lost. in this warzone, a transgirl trapped in the confederacy gets saved from that fate and finds one or more partners who will treat her the way she wants to be treated, and also gets one of the symbols of her past life replaced by a more appropriate one.