How bad is the commute from Danville or Alamo to San Francisco or the Peninsula?
If you're commuting to SF two or three days a week, it's very manageable. Most people drive to Walnut Creek or Pleasant Hill BART and ride about 35–40 minutes into the city. Door-to-door you're looking at roughly an hour, which is honestly comparable to what a lot of Peninsula commuters already deal with on Caltrain.
If your office is in South Bay — Mountain View, Palo Alto, Sunnyvale — that's a harder commute. 680 south to the San Mateo Bridge or Dumbarton can run 45 minutes to well over an hour depending on the day. I won't pretend that one's easy.
The honest answer is that Danville and Alamo work best if you're hybrid or remote a few days a week, which describes most of the families moving here right now. The return-to-office trend has settled into a two-to-three-days-in-the-office rhythm for most Bay Area tech and professional services companies, and that's exactly what makes this corridor work.