TASK: Potential fixup/followups for the allocator changes

These is a list of potential followups for gh-17582

Release note is missing? PR DOC: add release note and move NEP 49 to Final #20194
I would like a bit "hand holding" for the arr->flags |= NPY_OWNDATA user. I.e. tell users in some place, (maybe the flag documentation?) linked from the warning: Please use use a PyCapsule as the array base (this is simple, but you have to know about PyCapsule). (I could look into that myself.)
PyCapsule_GetPointer technically can set an error and may need the GIL? I am not worried enough about this to delay, but the functions look like they are meant to be callable without the GIL (I doubt we use it, and I doubt it really can error/need the GIL, but maybe we can make it a bit nicer anyway).
The void functions use (normally) small allocation: I think it may make more sense to just use the Python allocators rather than a (possibly slow) aligned allocator. (This is VOID_compare)
We should double check that we are OK without an explicit versioning mechanism (and maybe related with users assigning directly assigning the handler).

Anyone else have anything that might make sense to look into?

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