@AAQ, when it come to rules we follow the rules
from daf yomi discussions: you find ownerless money without simanim, you are allowed to take it.
You don’t have to. You can still make an effort too find the owner. If he is non-Jewish, this could be kiddush Hashem.
re: dog. It depends how people will see it. Someone with a dog is probably presumed to be disabled. Currently, someone without a mask is seen as non-complying, people will not think that he might have medically-certified masko-fobia