How to save Excel sheets to PDF using Python

Question

I have a multiple-sheet Excel spreadsheet. I require a Python script that will save each sheet as a PDF in landscape orientation, scaled to the pagewidth, with the sheet name serving as the PDF's filename. What I have so far thought of is as follows:

import pandas as pd
import openpyxl
from openpyxl.utils import get_column_letter
from openpyxl.worksheet.page import PageMargins

# Load the Excel spreadsheet
file_name = 'A1 Marking Rubric 2023 in progress.xlsx'
xl = pd.ExcelFile(file_name)

# For each sheet in the workbook, create a PDF
for sheet_name in xl.sheet_names:
    # Load the sheet into a DataFrame
    df = pd.read_excel(file_name, sheet_name=sheet_name)

    # Set the output file name
    pdf_file_name = f"{sheet_name}"

    # Get the sheet dimensions
    wb = openpyxl.load_workbook(file_name)
    ws = wb[sheet_name]
    max_col = ws.max_column
    max_row = ws.max_row

    # Calculate the page width
    page_width = sum(ws.column_dimensions[get_column_letter(
        i)].width for i in range(1, max_col+1))

    # Set the page margins
    page_margins = PageMargins(left=0.25, right=0.25, top=0.75, bottom=0.75)

    # Save the sheet as a PDF
    with pd.ExcelWriter(pdf_file_name, engine='openpyxl') as writer:
        df.to_excel(writer, sheet_name=sheet_name, index=False)
        wb = writer.book
        ws = wb[sheet_name]
        ws.page_margins = page_margins
        ws.page_setup.fitToWidth = 1
        ws.page_setup.fitToHeight = 0

    # Move the PDF to the current directory
    import os
    os.replace(pdf_file_name, f"./{pdf_file_name}.pdf")

I end up with the right number of files in the target folder, with the right names, but each of them is File not in PDF format or corrupted. The other questions on this topic don't use Python. Can anyone see the fault?