Reminder John Oliver in 1000% onboard with NATO imperialism. Always toes the NATO line, was a huge booster of the Hong Kong attempted color revolution, spews Zenz lies on China, etc, etc. AND is married to a Republican party operative (I don't think it's just for hate-sex).
John Oliver is best seen as CIA. Most media are but him especially because he's very savvy about it and appears progressive on the surface compared to a lot of the "journalist" ghouls.
DPRK. They should get them from the DPRK. Russia has a defense pact with the DPRK who has been sending them tons of shells for their war. The DPRK should be able to purchase s-400 systems at least and re-ship them to Iran if Russia doesn't raise a big stink about it.
s-400 are already sold to various countries. Russia already has deployed s-500 systems themselves against Ukraine and s-600 has been developed and is being fine-tuned. So it's not top of the line and no defense secrets are leaked most likely.
I have a doubt this will ever be possible to a meaningful degree. They have a contradiction, a very disagreeable one between hardline religious fundamentalists that most ethnic-religious minorities and a huge number of Shia dislike as too conservative, reactionary, and repressive and the liberal reformers whose domestic policy reforms of maybe allow women to show some hair and don't sick the religious morality police on young people dancing to music are very popular BUT who are naive and gullible towards the west and keep getting owned in foreign policy decisions. The liberals get in power and disgruntled hardliners may leak to make them look weak to get back their religious fundamentalist power over their people. Hardliners in power = disgruntled liberals, young people, minorities, etc. Besides that they killed communists, atheists are blackmailable because those are illegal, gay people are blackmailable, etc.