Hi FrancoisCi,
Thanks for posting in the community.
According to your description, my understanding is that you want to create a Workbook for users to upload related information and store it in a SharePoint list
If my understanding is right, you can refer to this post:Solved: Update Sharepoint List From Excel File - Power Platform Community (microsoft.com)
If you have more concerns about updating Sharepoint List From Excel File in PowerApps, since we have a specific channel Microsoft Power Apps Community coping with building Power Apps questions, I suggest you post a new thread there for expert help.
Thanks for your understanding.
Tin