Icelandic farmers' secret ingredient: volcanoes
weforum.org
weforum.org
As an comparison, wouldn't this do better that what the Netherlands using glasshouses heated by imported natural gas?
I think that your starting point for food has a reasonable claim for being the best in the world. I’m pretty sure everywhere is going to struggle.
Iceland has very high labor prices. Anything that needs a lot of human labor isn't going to be worthwhile as an export from Iceland. Tomatoes need picking and packaging by hand still, and while that's the case, it'll never be a major exporter.