1. Each country shares same catalog, same base prices, same shipment rules, same languages (english, french, german), but the featured products, promotions, banners, domain, are different per country.
Answer:
Create Different Store from Main website, Main website is default comes with magento native.
For Each country you need to set different store so you can share same catalog, same base price,same shipment rules and store wise language.
For Store wise you can set different url if you want from Stores -> Configuration -> General -> Web
set Base Url for Base Link Url your store.
2. The customer database and order database can be unique as well.
Customer database remains same for single website because you cant split customer database for different store from one website. Order Database is also remain same but order id for the different store will be different.
3.but the featured products, promotions, banners, domain, are different per country.
You can set Feature products, promotions banners will be keep different using Static block and CMS page with set Store view scope settings.
you need to Use GeoIP extension for keep featured product, promotions banner to use separately for a separate country. Otherwise you need to create store for a different country so you can easily manage Static block and CMS page based on store wise.
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