In the 19th century, Russia forced Iran to cede huge chunks of land in the Caucasus after a couple of wars. The change over to Soviets in Russia brought a brief pause but not before long the Soviets started to get into Northern Iran wanting access and use of their oil.
Reza Shah Pahlavi tried to keep Iran neutral during World War II, but with a growing German presence in the country, the UK and Soviets weren’t having it called a truce once Nazis violated the Soviet & Nazi treaty. In August 1941, they jointly invaded Iran to secure a vital supply line for Lend-Lease aid going to the Soviets. This invasion forced the removal of the Shah and put his young son on the throne, while the Allies effectively controlled the country.
After the war ended, the US, UK, and Soviets had pledged to leave. But only the US and UK followed through. The Soviets refused to go, instead backing separatist groups in Iran’s northern provinces and arming local forces to delay their departure. The Soviets had tried first to force Iran to surrender their oil to the Soviet Union. This led to a major international crisis in 1946, one of the first tense standoffs of the Cold War.
Honestly the UK, Soviets, and US abused and used Iran and why this gets ignored that they were occupied by joint UK/Soviet operation just a few years previously to this is wild.
I’d say Arch Linux if you are sure about doing something else than Proxmox. The wiki and help posted on the internet might benefit Arch switch currently. You can get the experience you are looking for and it doesn’t box you out of using Nix. Arch will get you going sooner IMO.
NixOS seems fun though and I’ve only recently starting messing with it. You will do best engaging with what you prefer best. The NixOS switch could pay better dividends in the future though.
If I recall this hasn’t been the first time NixOS has had to consider Palmer/Anduril. You could keep an eye out for the auxolotl project that is doing an alternative/fork of Nix.