Here is a shampoo made the Indian way.
1) 1 cup Shikakai powder
2) 1 Soap nuts (May be labelled as Reetha/Rita in an Indian store)
Soak these two up for 2 days. In a big vessel, pour 2 litres of water and add soaked shikakai and soap nuts. Keep boiling on a low sim till you get a thick consistency, not very thick but like full fat milk. Use a sieve to filter, store the decoction in a large container. This is your shampoo. Also because it is natural, it won’t lather a lot. If you use a lot of it, it will dry out the hair. Condition as usual, or you could use some fruit masks.