In the short term, most dogs will be able to eat human food without any issue.
However, long term, breads will contribute to dental issues, like teeth rotting. Since these are stray dogs, they don't have good dental in the first place.
I would really recommend normal dog food. Another idea is to check with the butcher shop if there is any fresh meat or scraps that you can use to feed dogs ; feeding raw meat is controversial, but you can also consider cooking the meat. Do not feed raw fish; too much room for parasites. You may be able to check charities in your area if they already have a service like this to feed stray animals. Or, alternatively, you could help solve the population by bringing the animals into an adoption shelter, if that is an option. I know that in some countries it is better for dogs to be on the streets than in the shelter, so use your best judgement.