I haven’t read any of these so can’t speak on them, ut here is a list of sources for the Wikipedia page in the subject:

Bittner, Donald F. (1983). The Lion and the White Falcon: Britain and Iceland in the World War II Era. Hamden: Archon Books. ISBN 0-208-01956-1.

Cadogan, Sir Alexander George Montagu (1971). Dilks, David (ed.). The diaries of Sir Alexander Cadogan, O.M., 1938–1945. London: Cassell. ISBN 0-304-93737-1.

Karlsson, Gunnar (2000). Iceland's 1100 Years: History of a Marginal Society. London: Hurst. ISBN 1-85065-420-4.

Magnúss, Gunnar M. (1947). Virkið í norðri: Hernám Íslands: I. bindi [Fortress North: Iceland Occupation: Volume I]. Reykjavík: Ísafoldarprentsmiðja. Miller, James (2003). The North Atlantic Front: Orkney, Shetland, Faroe and Iceland at War. Edinburgh: Birlinn. ISBN 1-84341-011-7.

Stacey, C. P. (1970). Arms, Men and Governments: The War Policies of Canada, 1939–1945. Ottawa: Queen's Printer. D2-5569. Archived from the original on 5 August 2014. Retrieved 3 July 2016.

Stacey, C. P. (1955). Official History of the Canadian Army in the Second World War, Vol. I: Six Years of War. Ottawa: Queen's Printer. Archived from the original on 1 April 2019. Retrieved 3 July 2016.

Whitehead, Þór (1999). Bretarnir koma: Ísland í síðari heimsstyrjöld [The British are coming: Iceland in World War II]. Reykjavík: Vaka-Helgafell. ISBN 9979-2-1435-X.

Whitehead, Þór (1995). Milli vonar og ótta: Ísland í síðari heimsstyrjöld [Between hope and fear: Iceland in World War II]. Reykjavík: Vaka-Helgafell. ISBN 9979-2-0317-X.

I think that depends heavily on who you ask. For example, not many in France would credit the USSR because the red army never set foot in France. On the contrary, I don’t believe any western powers set foot in Lithuania so they would probably credit Russia.

Then, as you mention there is a lot of nuance in certain countries not wanting to give other countries credit due to post-war relations.

I am not sure where to find the prices, but I know both started making well crafted leather luggage. I reckon these would be decently expensive even without the brand recognition they have today. I think they both didn’t get into clothing until later, where the markup of their brand is really highlighted.