I have asked several times via the trusted members forum and by email about rules about property listings but had no replies to date. I have however seen on the Google developers API site that several real estate companies do have their own maps powered by google maps on their own sites and are listed as examples by Google. I believe these were built with the Google API. They have an option to search for a property via map search and you just click on the flag for the property . It then opens Street view etc. I also think it may be possible to build your own local maps with google mapmaker (although this is being replaced soon )
This the link to RedFin Real Estate and also the Google API site if any help
https://www.redfin.com/city/17151/CA/San-Francisco/filter/viewport=37.77672:37.77246:-122.40792:-122.41556,no-outline
https://enterprise.google.com/maps/realestate/