Pretty sure my dog belonged to someone else. He ran into our yard one day and stayed for almost 2 weeks. No one came looking for him after a few posts to social media.
Did you take him to the vet to check for a microchip? (And get his health checked)
He wasn’t chipped / fixed at all when we took him to the vet. After the first two weeks we ended up just keeping him hoping the owners would eventually turn up.