Not a proper solution, but there are weatherproof plastic enclosures available. Look up 'waterproof wifi enclosure' on Amazon - there are several available.  A non-wifi plastic waterproof electronics enclosure might work just as well and be cheaper.  To power it, a USB POE injector can inject power into a weatherproof CAT6 ethernet cable, then drill a hole in your wall feed the cable through, and fill up with sealant. In the enclosure, a USB POE splitter can extract power from the ethernet cable and feed it into the eero.  Injectors and splitters are cheap, and this avoids running a mains power cable outside the house.  Test everything before drilling holes in walls ...