May Allah reward you, Shaykh. There is a second question: Are there specific surahs for the Duha prayer?

That you recite in it, or any dhikr after finishing the Duha prayer? I do not know anything about that. Rather, the Prophet ﷺ.

And encouraging it, as came in the narration of Abu Huraira, in his saying: My khalil advised me with three things, and he mentioned among them the Duha prayer.

And this also came in many narrations, from the narration of Abu Dharr, as well as the narration of Umm Hani and others, from the Prophet ﷺ, regarding the virtue of the Duha prayer and encouraging it.

As for dhikr in it, its length, and the like, I do not know of any evidence from the Prophet ﷺ regarding that.