We’re taking the southern route crossing at least 21 countries. We’re planning on taking the ferry across the Caspian Sea from Azerbaijan to Turkmenistan but we might see if we can blag our way into Iran.
The orange pins are the Iran detour and the redish/purple pins are the Pamir Highway, one of the most anticipated parts of the route. You have to get an additional permit for this region of Tajikistan but it’s apparently well worth it. See this post on it for a taster