I have one "weird" and "radical" proposal: public housing to rent. Not to but. At affordable price. That would lower the price of every house, flat, ...
That same article says it clear: the lion's share is the taxes part, not the house. If there was a public program, the taxes should be far lower. After all, that project wouldn't be a for profit one.
"While hard costs have surged during the pandemic, thanks to complications like diminished trade and supply chain issues, Alameldin said San Francisco has long been “practically infamous” for driving up soft costs with long, volatile planning debates."
That "practically infamous" means is not just a tiny part of the price.