You're going to struggle to find a ND charity that is politically agnostic because as charities, they support people who's ability to live without poverty and ostracisation is extremely politically motivated, even if they claim to be non-partisan.
And when you say all neurodivergences, can you elaborate. Do you mean, literally all of them?
So not just ADHD and autism, but dyslexia, dyspraxia, dyscalculia, dysgraphia, tourettes, but other lesser considered and possibly comorbid conditions like selective mutism, speech apraxia, OCD, epilepsy, intellectual disabilities and sensory processing disorder?
If the latter then I'm afraid it is an impossible task, but if the former it will still be difficult because each charity usually caters to specific needs each condition presents with.
The adhd foundation may meet your criteria as they do actually support all neurodivergent conditions, however their approach is mostly adhd centric, and less mainstream profiles might not find the same level of tailored material.
On paper I think they meet your criteria but in practice I'm not really sure that they do, or that such a charity with your criteria exists.