Nanunanu;
the definition of a vagina could be best summed up as 'typical phenotypic expression of the XX genotype' eg embryological development of the Mullarian ducts, resulting in external (usually signalling associated internal) genital development recognised as of the female, ova producing sex.
now theres a wide variation in possible developmental issues, as with any other organs eg agenesis, dysgenesis, partial development, exaggerated development, virilisation; membranous issues such as haematocolpus may occur, while certain specific genetic conditions eg XY with androgen insensitivity may lead to phenotypic expression of the genome resulting in the embryological development of a 'default' mullarian system instead of Wollfian eg an intersex condition: As with any biological system there is a wide variation in physical development and phenotype, but none of these conditions existence invalidates the fact that there is a set of organs encoded by the X chromosome who's expression is used to recognise the indivdual at birth as ' looks female' eg potentially of the ova producing, childbearing class of our sexually dimorphic species' and assign them to this category no matter what physical or hormonal issues may go unrecognised until later in their life.
In any state of surgical alteration, with any changes to hormonal milieu, lubrication or muscle tone the internal genitalia of an individual who has a developed mullarian system are still distinct from a surgically constructed neovagina.
Whatever technique used to create a neovagina, (and its a fascinating subject to read round) whether it is part of a gender reassignment, or as a construction for an XX individual with agenesis or intersex genitalia; a neovagina is distinct from a 'native' vagina (for want of a better word)
A wide variety of approaches have been used eg penile inversion technique, a skin or omental graft, intestinal flap, or musculocutaneous flap or pedicle graft technique; but whatever method used to create a neovagina the idea is to create a pouch that may be used for intercourse (eg fulfils one potential function of a vagina)
but the tissues of a neovagina and their relationship to other organs/blood supply/sensation/hormone release/microflora etc will be distinct from that of an embryologically developed 'native' organ
and I can see why many people in possession of a vagina are a bit
at having the complexity of their body and physiology being directly equated with a 'pouch' or hole to allow intercourse
Its a bit disingenuous to equate surgical changes, hormonal changes and muscle tone changes is somehow directly equivalent to a surgically approximate construction of the female external genitalia