As a shop owner I still want to show former products and their variants to users and keep the URLs valid.

Only recent versions and products not excluded from search should appear within the in-store search.

https://store.shopware.com/de/esmx267827209428m/artikel-aus-suche-ausschliessen.html lists the extension's feature to be available with Shopware 6.

Actually it is not.

While you can exclude a product to appear in listings and you being able to exclude it from listings AND search ... there is no option to exclude it from search only.