How do other hackers survive WiFi client isolation?

Google just replaced my Fiber Router with Google Wifi (I moved residences) and the new gear will not allow regular connections between peers. Google will not support regular LAN operation on the private side of the NAT. This also happened to my parents when their neighborhood upgraded to fiber and new routers were deployed. I ended helping them talk to AT&T support for AN HOUR before they admitted to client isolation and offered to remove it.

This frustrates regular servers (starting with the Home Assistant instance I used to use) and requires I build a second network or buy different gear. Google's response was something vague about "cloud enabled." Thanks, I can reach the cloud hundreds of miles away but I'm isolated from devices across the room.

I'm writing to HN in case anyone has a verified solution (e.g. will double-NAT work or do I have to masquerade a public IP to it?) and other useful discussion. I've already started shopping Ubiquiti but would probably just as happy or happier going back to an iptables based router on my own hardware.