Yeah this data is usually maintained at the county level and is accessible through the state assessor office. This website is something some activists made that sits on top of that data.

But… There’s usually an ArcGIS server for any county in the US and that gives details on each “Tax Parcel” of land and often says who owns it. Although, knowing when two owners are the same people is tricky. Just search “your city/county arcgis tax parcel” and there might be a fancy webmap made by the county.

With some scripting you can trivially dump these databases, as they all use the same API and have zero secruity since its all public data.