For sea ice you can look at the Snow depth layer whose ECMWF title is Snow depth and sea ice. This layer clearly shows that the Oslo Fjord is covered in ice.
DB143B08-2F32-4B74-989E-B9E19905F3B1.jpeg
(Note this layer for snow depth is not very accurate in mountains due to the medium resolution of the ECMWF model)
But this layer in Windy does not show that the Gulf of Bothnia is also covered by sea ice, as this ECWMF map shows.
https://charts.ecmwf.int/products/medium-snow-sic?base_time=202401090000&projection=opencharts_north_west_europe&valid_time=202401090000
I guess Windy only selects the tiles along the shoreline for this layer. it would be interesting to show this parameter over the entire maritime areas.
About the Waves parameter showing sea ice areas, see what the ECMWF says :
“ Where sea ice cover >30% all wave parameters are set to missing (i.e. no valid values). Wave products near ice-edges may be of lower quality than for the open ocean. This may be due to uncertainty in sea-ice cover, or in the detail of an ice edge and consequently also in the boundary of the water area. ”