There are websites you can search online to help find your missing pet
and we all hope for the best someone does the right thing.
Nextdoor.com
Facebook.com
Petharbor.com
https://sanantonio.craigslist.org/
Google.com
The BEST option for you to do is make sure your pets are up to date on vaccines and microchipped. So when the founder brings the lost pet to get the microchip scanned and the microchip is updated and current online registration.
The veterinary office will call you and reunite you with your pet. :)
Where can I register my microchip?
You have your personal companion registered, normally its registered at the vet's or clinic of your choice office. One I can recommend its a free pet registry. https://www.freepetchipregistry.com/login/
I personally tried it out. I have registered 5 animals with different microchip vendors that were listed. And the best part is that I didn't have to pay the renewal fee that was due from the other microchip vendors they have their own personal website. I think there is a least a dozen different microchip vendors that they list or even more.