Westwind:
https://maptools.com/
All mapping tools come with a learning curve. This one isn't too bad, and there are handy tutorial videos.
I was about to suggest this one because it is tokens on tiles based (not that others are not). However, if you mouse over the tile, or look at it in certain menus, it identifies the tile.
I am wondering if a visually impaired or blind user couldn't use some kind of reader to get an audio cue of what the token is read out aloud when it was moused over. There could be technical limitations that would preclude this from working and I would imagine there are.
It wouldn't solve the problem of being able to "draw", but if the user used a certain type of tile for empty space, it might at least give a way to place objects and characters in a physical space in relation to one another.
Another possibility is using zonal movement like FATE (the game system) uses. Imagine the space in which the action is happening on a 3x3 grid. I choose a low number so it's possible someone who is not sighted could feasibly keep track of this mentally, but high enough it's still interesting.
Characters, objects etc. could be said to be in the top left, top middle, top right, middle left, center, middle right, bottom left, bottom middle, and bottom right positions. Characters can attack in melee or hand to hand any opponent in the same position (so two people in the top right together can punch each other). Characters can be assumed to be able to launch ranged attacks at least one square away, more if the game master believes it makes sense (so someone in top right can throw a rock at anyone on the top middle, top right, center, or middle right positions).
It's not a true "map", but it would give the semblance of tactical positioning on a grid that so many games use just with lower precision. Essentially it's the FATE rules, but instead of drawing the zones with irregular but sensible lines, it's strictly a grid with as many squares as the gamemaster can mentally make sense of without being able to see it.
And no it's not a perfect solution but I am just brainstorming here.