Setting `accuracy` parameter in the `pyproj.Transformer` class

This is a question about how to set the accuracy parameter in the Transformer class.

I have UK Northing/Easting (EPSG:27700) data held in the variable DATA and would like to project this to WGS 84 (EPSG:4326) to a given level of accuracy using pyproj as set out in the following code snippet:

from pyproj import Transformer, CRS
from shapely.ops import transform
transformer = Transformer.from_crs(DATA.crs, CRS.from_epsg(4326), always_xy=True)

From the API I understand that the Transformer accuracy parameter is in metres and defaults to -1.0. If I wanted to set this accuracy to an arbitrary distance, say, 0.5m, how do I do this?

My naïve attempts to set the value as below fail with a can't set attribute error:

-1.0
>>> transformer.accuracy = 0.5
Traceback (most recent call last):
  AttributeError: can't set attribute
>>> transformer['accuracy'] = 0.5
Traceback (most recent call last):
  AttributeError: can't set attribute

I have looked and couldn’t see answer in the usual places.

[snowman2]

The accuracy is just for information. So, no behavior change.

numpy can help with the decimal precision: https://numpy.org/devdocs/reference/generated/numpy.around.html#numpy.around

[snowman2]

https://www.explainxkcd.com/wiki/index.php/2170:_Coordinate_Precision