Yes, even project-specific products such as windows, doors, concrete elements, etc. need to have a GTIN to which you can connect product information and product data.
There will be a guide on how to create a unique GTIN for these, that is expected to be completed in the first half of 2022.
This is based on a guide developed by the construction industry in Norway and which is now being adapted to the Swedish construction industry. It states that project-unique articles must be assigned a new GTIN for each project-unique configuration, which is in accordance with one of the main rules in the GTIN management rules.