I'm on the east coast, but I'm participating in a mutual aid network that does exactly this kind of thing. Try googling your local branch of the Democratic Socialists of America (I think you're in Silicon Valley DSA's territory). Each chapter is independent and not great at communication with each other, but I found a web page that said SV DSA is doing grocery delivery mutual aid for elevated risk people. I don't want to post it here because I don't want them to get trolled, but it's easily to google.

I only mentioned DSA because I'm member of the national org, but there are probably many other organizations doing similar work. Please be safe and stay healthy! Good luck!

Edit: Just want to emphasize to people in a similar situation, that the key words to search for are "Mutual Aid" on google, facebook, and twitter if you don't know someone already connected to an organization. Many of these orgs are also looking for volunteers.