I think I read somewhere that Latvia exempts its own athletes (in all disciplines) from quarantine but I'm not sure about international ones. There may be some additional rules that we haven't found though. For Germany it was either quarantine or a negative Covid test result if you came from a risk area.
I'll try to see if Poland is an option for Sondre (not that the situation is great but the Warsaw Cup is go as of today). In August international athletes competing in high level international competitions in Poland were made exempt from quarantine but I'm not sure if it's still the case now.
I don´t think Poland is an option for Sondre. It´s possible that athletes would enter the country without quarantine, but Poland is now way over the requirements for going into Norway without quarantine, and i´m not sure he would take the risk of 10 days without practice and possible expose himself for Covid.
As I was writing the post earlier about Latvia (I seem to jinx it), Norway changed the travel advices and there are now no countries in which doesn´t require 10 days of self-isolation/quarantine upon arrival to Norway. (Except a few regions in the nordic countries). Latvia is now just above requirement, but if they get control over the new cases they might be under again. That is my hope, but then again, it´s the question if they would let athletes in without quarantine.
To be honest, I don´t think Sondre will have the chance to compete international before earliest 2021, because of the whole Covid-situation. Either he would have to self-isolate in 10 days after returning home, which he and his team probably isn´t considering as an option or I think we would have seen him at NT. And the few countries which might be an option because of low numbers, probably won´t let him in because of strict travel advices. And it kinda makes sense because such countries probably have low numbers because of the measures...
We might see his new programs at Norwegian Championship in January. It was streamed last year, so i´m sure they will do it this year also.
I had a wild thought that Sondre might go back to Oberstdorf to train again just to be able to get some international comps and competing exercise. We have seen some strange/necessary coach changes so far because of the pandemic and closed borders. With the travel restrictions we have in Norway it would be really difficult for him to achieve his goals for going to WC and OG. And because he doesn´t have the technical requirements yet, he really doesn´t have many comps to loose. Maybe he could go back to Mr. Huth. Not sure if it´s an option though. I´m also dreaming about him being coached by Lambiel

(Wild dreaming, I know).
Well he moved back to Norway because he missed his social life and everyday life, and with the travel restrictions and all it´s probably not likely that he would make such a move, but... you know. It was just a thought. He might not go for another OG if he doesn´t get to the next one, so maybe he has to make sacrifices to get there.