Let me take your post bit by bit:
To me, the fundamentals of some of the arguments made here attempting to paint trans women as an opressor of cis women
The argument is that males are oppressors of women. This is the basic tenet of radical feminism. Trans or whatever, it's the sex of people that matters.
The trans community as a whole is so marginalised, I cant see how anyone can make this claim with a straight face.
Have you heard of intersectionality? Roxane Gay has a good essay on how privilege and oppression can coexist, usually do coexist in the same person or situation. Trans people may well face problems in their lives; this doesn't mean they don't also have some advantages, specifically, males benefit from male advantages. These include both physical advantages like freedom from some of the issues I listed before, and socialised advantages (female socialisation starts from pre-birth).
Those same people are yet to provide me with any insight into how trans women are anything other than allies
Yes, some transwomen are allies to women. Debbie Hayton, Miranda Yardley, some posters on here, too, are all very aware of the issues women face (and also realistic about their own sex status, fwiw).
the default for some of the posters here is that trans women are still men, which whilst the majority opinion here, isnt reflective of the outside world.
In what way is a transwoman not male? This is just the very straightforward statement of fact. If it weren't, there would be no need for the 'trans' bit at the beginning.
Don't shame me for having a heart. Shame on those who would seek to deny acceptance and equality for others int he name of feminism.
Your heart is apparently cognisant of the difficulties faced by transwomen. That's great. Feminists on here centre women, and our hearts are focussed on the possibility of liberating women.
As for acceptance and equality - what does this actually mean? Trans rights are human rights? Fine. Great. Of course transpeople deserve the same rights as everyone else. They just can't have more rights than others, or rights that impinge on other people's. If a woman with a trauma history that means she is terrified of males, and is on a hospital ward with a transwoman whom she is sure is going to attack her, is that bigotry? If a rapist is put into a woman's history because of self identifying as a woman, is that fair? Genuinely?
Do you not have any compassion for the terrified woman in the hospital ward, for the woman in prison who has been a victim of sexual assault from a transwoman?
You're totally free to centre transwomen over women, of course. That's your choice. But don't be surprised if, on the 'feminism' board, you encounter women who disagree.