Yes. Other than some corridors like El Camino, the industrial or office zones, or the various downtown areas, most of the peninsula are suburbs.

The El Camino corridor, an almost-continuous strip mall, is as quintessentially suburban as it gets.

Some parts are pretty built up with mixed use mid rises these days.

Agreed that it needs to get developed much more.

There are lots of houses and open space south of SF.

But it is mostly classified as urban, officially at least, until you get quite away from SF or hit the hills.

I wouldn't call large parts of SF itself urban because the density is so low.