What remains constant, regardless of those disagreements, is the experience of dysphoria itself. That experience doesn’t depend on adopting any particular theory about sex or gender.
This isn't true for the fetishists. Obviously this thread is about children and the majority of the fetishists are adult men. Unfortunately though, some adolescent males are being drawn towards this lifestyle way of "being" trans.
The (initially*) difficult part is how to spot the difference between a fetishist who feigns having distressing dysphoria and someone who really does have distressing dysphoria.
An adult fetishist's experience of "dysphoria" is actually a much-enjoyed exercise in sexual gratification. Positioning it as distressing to garner sympathy is part of the gratification. Getting called out on it can also be a part of that, similar to a dominatrix/submissive fantasy.
*This gets easier the more aware one becomes of the clues that give away the fetish.
This is an interesting blog that was written by an adult male fetishist who recognises why this problem is damaging for women's rights:
https://archive.is/2pQIq
He doesn't cover the impact on children, so it's not directly relevant to this thread, but it provides some interesting insight into a world that is indirectly relevant to all the children who believe themselves to have a gender identity that differs from their sex: to borrow a quote from his blog "to my mind, it's the key, heart, core and crux of the problem with the trans movement today."
Note that he concedes it's not always easy to know whether someone's dysphoria is actually a fetish or not. In a few of his named examples of people who aren't fetishists, he is hesitant to say for certain.
Edited to remove superfluous words/repetition.