Python example on how to manipulate USD_UserExportedAttributesJson attribute on nodes to define how Maya USD exports custom attributes to the USD attribute names

maya_usd_export_set_user_exported_attributes_json.py

from typing import Any
from maya import cmds
import json

ATTR: str = "USD_UserExportedAttributesJson"

def add_explicit_attribute_export_name(
    node: str, 
    maya_attribute_name: str, 
    usd_attribute_name: str
):
    """Set usd export attribute name for the maya attribute on the maya node."""
    # Ensure attribute exists
    if not cmds.attributeQuery(ATTR, node=node, exists=True):
       cmds.addAttr(node, ln=ATTR, dt="string")
    plug: str = f"{node}.{ATTR}"
    json_str: str = cmds.getAttr(plug) or "{}"
    data: dict[str, dict[str, Any]] = json.loads(json_str)
    data[maya_attribute_name] = {"usdAttrName": usd_attribute_name}
    json_str: str = json.dumps(data)
    cmds.setAttr(plug, json_str, type="string")


def remove_explicit_attribute_mapping(node):
    """Remove USD_UserExportedAttributesJson attribute from node."""
    if not cmds.attributeQuery(ATTR, node=node, exists=True):
        cmds.deleteAttr(f"{node}.{ATTR}")


for node in cmds.ls(selection=True):
    add_explicit_attribute_export_name(
        node,
        maya_attribute_name="myAttribute", 
        usd_attribute_name="userProperties:myAttribute"
    )
    add_explicit_attribute_export_name(
        node,
        maya_attribute_name="myOtherAttribute", 
        usd_attribute_name="userProperties:myOtherAttribute"
    )