I’m assuming you host your own dictionary files, so you should be able to add new ones. Chromium itself doesn’t include Icelandic spell checking for whatever reason
There’s already a CC BY-SA 3.0 project for the aff and dic files. It’s used by Libreoffice
Then I understand there’s an internal chromium tool convert_dict to turn them into bdict that can be added to chromium browsers
I think this should be fairly easy to add and useful to any Icelander. I can definitely recommend it to more people then. Thank you!