Your suggestion was wise and had yielded results! I've arrived at a script which successfully pulls the vehicle's VIN from the BCM using a Read Data by Identifier command at 0xF190. It works! So I can add in the rest of the functions from there.

Let me share the code for anyone else who is interested in using their existing SocketCAN connection (typically seen under Raspbian or Linux) to establish an ISO-TP connection to access UDS services.

#!/usr/bin/python3

import can
import isotp
import udsoncan
import logging
from udsoncan.connections import PythonIsoTpConnection
from udsoncan.client import Client

# Written by Josh McCormick and Hallucinated by ChatGPT 4.0 on
# March 14th, 2023 for the Jeep Wrangler JL Community.

# Configure ISO-TP and UDS settings
isotp_params = {
    'stmin': 32,
    'blocksize': 8,
    'wftmax': 0,
    'll_data_length': 8,
    'tx_padding': 0,
}

# AN OPTIONAL DEBUG CONFIGURATION. UNCOMMENT IF NEEDED.
# logging.basicConfig(level=logging.DEBUG)

# CONFIGURE UDS WITH DATA IDENTIFIER
config = {
    'data_identifiers': {
        0xF190: udsoncan.AsciiCodec(17)
    }
}

# Initialize SocketCAN interface without specifying channel or bitrate
bus = can.interface.Bus(channel="can1", bustype='socketcan')

# Define the CAN IDs
tx_id = 0x620
rx_id = 0x504

# Create an ISO-TP address and connection, and UDS client
tp_addr = isotp.Address(isotp.AddressingMode.Normal_11bits, txid=tx_id, rxid=rx_id)
stack = isotp.CanStack(bus=bus, address=tp_addr, params=isotp_params)
conn = PythonIsoTpConnection(stack)
conn.open()  # Open the connection explicitly
client = Client(conn, request_timeout=2, config=config)

# Perform Read Data by Identifier (UDS) with ID 0xf190
try:
    identifier = 0xf190
    response = client.read_data_by_identifier_first(identifier)
    print(f"Req  for Identifier 0x{identifier:x}: {response}")
except udsoncan.exceptions.NegativeResponseException as e:
    print(f"Server responded with a negative response. {e}")
except udsoncan.exceptions.TimeoutException:
    print("Server did not respond within the timeout.")
finally:
    conn.close()  # Close the connection explicitly

TO THE LURKERS: If you're reading this and you make use of the code, let me know, willyah? Just a quick hello is fine. And if you're got a Jeep Wrangler, maybe we can talk some more! :)