要解决这个问题，需要使用 Microsoft Graph API 与 OneDrive 进行交互。首先，需要授权用户进行访问：

from msal import PublicClientApplication

app = PublicClientApplication(client_id='',
                              authority='https://login.microsoftonline.com/common')

result = None
accounts = app.get_accounts()
if accounts:
    chosen = accounts[0]
    result = app.acquire_token_silent(scopes=['User.Read', 'Files.Read.All'], 
                                      account=chosen)
if not result:
    flow = app.initiate_device_flow(scopes=['User.Read', 'Files.Read.All'])
    print(flow['message'])
    result = app.acquire_token_by_device_flow(flow)

接下来，需要使用得到的访问令牌获取 OneDrive 中所有 Excel 文件。可以使用 https://graph.microsoft.com/v1.0/me/drive/root:/path/to/folder:/children 的 API 来获取指定文件夹下的所有文件。需要将 path/to/folder 替换为实际的文件夹路径。

import requests

url = 'https://graph.microsoft.com/v1.0/me/drive/root:/path/to/folder:/children'
headers = {'Authorization': f'Bearer {result["access_token"]}'}
response = requests.get(url, headers=headers)
if response.status_code == 200:
    files = response.json()['value']
else:
    print(response.text)

最后，可以使用 openpyxl 模块来遍历 Excel 文件。

import openpyxl

for file in files:
    if file['file']['mimeType'] == 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet':
        url = file['@microsoft.graph.downloadUrl']
        response = requests.get(url, headers=headers)
        workbook = openpyxl.load_workbook(filename='temp.xlsx', data_only=True)
        sheets = workbook.sheetnames
        for sheet in sheets:
            worksheet = workbook[sheet]
            for row in worksheet.iter_rows():
                for cell in row:
                    print(cell.value)