How to sync external system Products and categories having special character names to Sitecore Commerce 9.2, if the original name map to display name it will have impact on SEO, as the site needs to show the exact name as it is in the external system.
You can extend SellableItem entity with your custom component and store synced Products and Categories names in that component.
For the display name you can adapt product name, based on SEO requirements. So it means, that you don't need to store the real product name from the external system in product display name field, instead of that you can store it in any custom component field.
More details how you can configure SEO-friendly URLs you can find here: