How do I validate SIRET + TVA intracommunautaire in Magento?

Two French B2B identifiers, two different validators:

• SIRET (Système d’Identification du Répertoire des Etablissements), 14-digit number identifying a specific establishment of a French company. Validated against the SIRENE database (free API from INSEE).
• TVA intracommunautaire (TVA intracom), format FR + 2 check digits + 9-digit SIREN. Validated via the VIES VAT service (EU-wide).

For Magento B2B we:

1. Add SIRET + TVA intracom fields to the customer entity (or B2B company if you’re on Adobe Commerce).
2. Validate SIRET against the SIRENE API on registration, rejects invalid / closed companies, auto-fills company name + address.
3. Validate TVA intracom against VIES, required for cross-border zero-rated B2B sales (intra-EU).
4. Apply 0% TVA on B2B intra-EU sales with a valid VIES-validated TVA number (reverse charge); 20% on B2C and FR→FR B2B.
5. Cache validations 30 days, re-validate on any address change.