FWIW, a single eero device cannot do this. With eero you get one main network, one (optional) guest network. That's it. (Hypothetically you could have two or more eeros but configure them as completely separate networks.) Amazon's design philosophy with eero devices is simplicity, for better or worse.
What you
could do if you want an additional wireless network (even with eero-provided main and guest wireless networks) is to add another wireless router or access point for the "pedestrian" devices. Maybe that's an old 2.4 GHz-only wireless router running
OpenWrt or DD-WRT, for example — something old you have lying around (or can buy for $5? or pull out of a recycling bin?) that can run current community firmware. You'd typically plug that old wireless router into a second port (if available) on the ONT or ONR so it's reasonably segregated from your other wireless network(s). Maybe it even supports 5 GHz band, but you shut off the 5 GHz radio since you only care about providing an IoT network in the 2.4 GHz band. Or you turn on the 5 GHz radio but configure it for 20 MHz wide Channel 165. Problem solved!
If you're shopping for a used, cheap (or free?) wireless router that can run OpenWrt for these purposes, consult OpenWrt's device compatibility table and also make sure you're getting a device that has at least 128MB of RAM and at least 16MB (preferably 32MB) of flash. With those capacities, or better, it'll be reasonably futureproof and allow you to run new releases of OpenWrt for many years to come.
and 2 AC Adaptors. I moved away from a centralised dedicated IoT router setup because it was on an Ikea rack and it was ugly 
