I’ve been to both Petsamo and Karelia, and trust me, we don’t want them back. To clean them up and bring them into modern standards of infrastructure would be ridiculously expensive. Not to mention the Russian population that has integrated in them over the last 80 years.

I recently read the Bobiverse books, and those were quite fun.

Daniel Suarez is another good one (start with Daemon), as is Ian McDonald (Dervish House, the Luna series).