Allow guests to see each other and access my local network separately

Yep, this functionality was there in the past and needs to be added back.

There's a more detailed discussion about it here:

https://community.netgear.com/t5/Idea-Exchange-For-Home/R8000-Guest-Network-Needs-Separated-Wireless-Isolation-and-Local/idi-p/1050376/page/3#comments

Its pretty silly when you look at the list of ideas that are under "Engineering Investigation".   vs. this one that is represented in 50 different ways across the 337 "New Ideas".  Most of the ideas they are actually considering have almost no votes.  God forbid they should work on something that lots of people want and is actually useful, instead of working on things like the ability to "add device icons" (LMFAO).