Do you know any sources for learning about about worship of Iris and Hestia in Ancient Greece?
For works specialized on Hestia, I'd start with these two works below. One is a master's thesis, the other is an article:
The Study of the Concept of the Sacred Hearth and Greek Goddess of the Hearth and their Association with the Prytaneion, its Origins and its Development by Esra Çayir
Hestia Hearth, Goddess, and Cult by Mika Kajava
You can also take a look at the first section of this other Master's thesis but it is more focused on the comparative analysis of the ancient cult of Hestia and the modern Olympic Flame. And if you haven't already, don't forget to look for smaller sections about her in more general books on ancient cults (eg. Ancient Greek Cults A Guide by Jennifer Larson has a page on Hestia). It might not be very useful if you're looking for specialized studies, but it can help if you've just started researching her.
Iris is a more complex case since, as far as I know, we don't have any actual cultic evidence for her outside of literature and her link to Hera. There is this Master's thesis. However, I can't tell you much about it since I never had access to it in full. The table of content doesn't indicate anything about cult either. I would advise to probably take the angle of researching Hera in the hopes to find mentions of Iris as her messenger and retinue, but I'm also afraid that even then, we'd come back to a lack of material when it comes to actual cult.
