3 and 5 are i2c, that can be shared as long as there is no address conflict.
The enviro uses 0x49, 0x29, 0x1d and 0x77, and the automation 0x48, so no conflict. Those pins would have been Red on the Phat Stack Configurator if there was an address conflict.
The black hat mini, https://shop.pimoroni.com/products/mini-black-hat-hack3r is one way to mount the two to one Pi. Or the phat Stack. With the pHat stack, if you use a female header, pointing down the same as on a phat, on your PI zero. You can plug your zero in just like it was a pHat, and not have to use a ribbon cable. You can do the same thing with the mini black hat hacker board, you’ll run out of space though trying to plug two pHats and the Pi in.