Multi-region, US ASTM vs EU EN 71 vs UK CA standards, how do you handle the catalog?

Three different labeling regimes for the same SKU when you sell internationally:

• US, ASTM D-4236 conformance + California Prop 65 warning on listed chemicals.
• EU, EN 71-3 (toy safety / heavy metals), REACH SVHC (substances of very high concern), CLP regulation (hazardous substance classification + labeling). Plus VAT-inclusive pricing display.
• UK, UKCA marking (replaced EU CE post-Brexit), BS 7272 for writing instruments. VAT-inclusive pricing.

The Magento architecture:

• Multi-Store-View per region, us_store, eu_store, uk_store, au_store. Same SKU pool, different PDP rendering.
• Per-region attribute scope, ASTM label only renders on US store view; EN 71 / REACH renders on EU; UKCA renders on UK. Custom Hyvä PDP template reads the region attribute and conditionally renders.
• Per-region pricing + currency, USD VAT-excluded for US, EUR VAT-included for EU, GBP VAT-included for UK. Magento ships this native.
• Source-selection (MSI), EU customers default-route to EU warehouse stock, US to US warehouse, etc. Cross-region shipments are blocked at cart for hazmat SKUs (international air freight prohibited).
• Cookie / consent, GDPR for EU, CCPA for California, PECR for UK. Handled by the consent-management module per store view.

The compliance data piece: Akeneo or Pimcore PIM as the source of truth. Brands ship ASTM + EN 71 + UKCA labels in the product feed; PIM normalises and pushes to Magento with the right attribute per region. Trying to maintain this in Magento admin alone breaks above ~5,000 SKUs.