I've said this before. You don't need anyone's permission to work on accessibility.
Build that feature accessible from the start. Then show decision-makers what they'd be rejecting.
When accessibility is already there, "no" becomes the hard choice.
They'd have to justify ripping it out. They'd need to defend why they want less reach, more risk or a smaller market.
Here's the thing.
You don't always have decision making powers. Accessibility needs to be accepted by those who do. You need to create the conditions to make that happen.
You need to create the conditions where approval is the path of least resistance.
Making the accessible version the default they'd have to actively undo is one such path.