A script to export attachments from ArcGIS Pro 3, based on a "CleanID" field on the base (non-attach) table. Will export files in the passed directory, named like `ATT{CLEAN_ID}.jpg`

ExportAttachments.py

import os
from functools import lru_cache

import arcpy
from arcpy import da

base_table = arcpy.GetParameterAsText(0)
files_dir = arcpy.GetParameterAsText(1)

if not (base_table and files_dir):
    arcpy.AddError("Expected two arguments: the base table, and a directory to save files")

if base_table.endswith("__ATTACH"):
    arcpy.AddWarning("Expected a base table as first parameter, does it really end in __ATTACH already?")

attach_table = base_table + "__ATTACH"


@lru_cache(maxsize=1024)
def get_clean_id(global_id) -> str:
    global_id = str(global_id)
    field = arcpy.AddFieldDelimiters(base_table, "GlobalID")

    where_clause = "{} = '{}'".format(field, global_id)

    with da.SearchCursor(base_table, ["GlobalID", "CleanID"], where_clause) as cursor:
        items = list(cursor)
        if len(items) != 1:
            raise Exception("Expected a single item in the base table with global id")
        item = items[0]
        return str(item[1])


with da.SearchCursor(attach_table, ['DATA', "REL_GLOBALID", "ATT_NAME"]) as cursor:
    for item in cursor:
        data, rel_globalid, att_name = item
        att_name = str(att_name)

        if "." not in att_name:
            # Take a guess
            att_name += ".jpg"

        clean_id = get_clean_id(rel_globalid)

        # Modify this line to change the file name, the first `{}` will be replaced with the clean_id,
        # the second `{}` will be replaced by the "ATT_NAME` field from the attach table ("Photo 1.jpg")
        filename = "ATT_{}_{}".format(clean_id, att_name)
        with open(files_dir + os.sep + filename, "wb") as f:
            f.write(data.tobytes())
        del data
        del item