https://katagobooks.org/ has now been updated with a deep analysis of 8x8!
The level of uncertainty in the analysis is higher than 7x7, but if you’re curious what all the optimal openings likely are in 8x8, you can explore the variations yourself at https://katagobooks.org/, and there is a high level overview here: KataGo Opening Books - 8x8 Highlights and Discoveries