Interesting. The 'pivot' from plain patruljeskibe to arktiske skibe was announced by the Forsvarsministeriet on 29 Jan 2025. A Thetis class replacement - OMT's MPV80 - was originally meant to have entered service sometime this year.
But the base MPV80 is 84 m long whereas, if this new arktiske skibe is just under 120 m loa, it will be slightly longer than the Thetis class frigates that it will replace. And 500 t heavier. (So also a bit longer than Canada's Harry DeWolf class AOPS but at least 1,500 t lighter.)
If first delivery of the new ship is to be Q3 2029, Søværnet is already 4 years behind schedule. Still, the reasoning seems sound. DK has concluded that SE and FI can handle the Baltic. Adding a larger, ice-hardened class as companions to the Knud Rasmussen class OPVs seems like a good idea.