Many societies covered their faces when outdoors all the time for practical reasons - to protect against the cold, the sun, dust, etc. Some for cultural or religious reasons.

Babies in as diverse of backgrounds as Alaskans to Arabians were raised for thousands of years with significant face-coverings donned before going outside as the norm.

Being worried about "facial expression in strangers in public" because people covered their mouths as a harm to your baby's development is... about 10 steps past absurd. This isn't even making mountain out of a mole hill, this is making a mountain out of a grain of sand.

And of course, compared to the risks of permanently-lowered IQ due to covid brain damage, or permanent lung damage or the various fatigue and other issues millions of people suffered from covid, the risk from the infection to a baby is literally millions of times worse.