…can be difficult, not only if it comes to buying (or leasing?) a new (or refurbished?) carpet. What actually is sustainable can be highly subjective. “Sustainability” labels are abundantly offered and it is often hard to understand which of them actually award products that fulfil relevant sustainability-related criteria.

To support consumers (or rather “users”) of various types of products in making well informed choices, different sources can be consulted – one of them is “Siegelklarheit”: https://www.siegelklarheit.de/en/siegel.
The guidance provided at such websites can be helpful, nevertheless (as with every source that evaluates sustainability-related information and service offers) every user should determine for themselves, how they make use of the guidance provided. It can be helpful to study the methodology which is used for the assessments of the sustainability labels (https://www.siegelklarheit.de/en/assessment-methodology).

Another example provided by the European Commission:
https://energy-efficient-products.ec.europa.eu/index_en.