The Danish page files these firms under Låsesmed & døre (locksmith and doors). A name here can be a locksmith, a door firm, or both. Ask which job they are pricing, and ask for the CVR number on the invoice.
In København most jobs are in apartment buildings: Vesterbro, Nørrebro, Østerbro, Amager and Frederiksberg. Access, parking, and whether scaffolding can stand in the courtyard move the price more than the postcode. The same 1 businesses as the Danish page: Glarmester Jannik Christensen ApS.