Start with the legal and workflow scope
List the French VAT-liable entities, domestic B2B sales, supplier invoices, B2C or cross-border transactions, services with payment reporting, credit notes and self-billing cases. France’s reform is not only outbound B2B invoicing: official guidance also distinguishes e-invoicing, transaction e-reporting and payment e-reporting. Your integration design should therefore start with invoice flows, not with a connector catalogue.