Unique case with the 49ers. Most teams will not be allowed to have fans in an indoor arena, but they will be allowed to play. I do not believe San Jose is in the same county as Santa Clara, but could be wrong.
The Sharks and 49ers are in the same county, yes.
Also MLS Earthquakes. NCAA SJSU FB, etc.
Sharks studio host Brodie Brazil on his YT channel yesterday was reading small, fine print of ruling. (Thinking about whether restrictions will be extended from 12/21 deadline.) Indoor sports (hockey, basketball) are differentiated from outdoors (football, soccer), a little. But teams can't travel to play elsewhere and return. And no touching (must maintain 6 feet social distancing at all times); that's ok for tennis or golf, but not a lot of other sports.
SJSU is hunkered in Las Vegas (old UNLV stadium, playing conference championship game Saturday).
49ers are hunkered in Arizona (playing at NFL Arizona).
Brodie suggests that rules for PRO teams be tweaked as they do have the resources to properly test, etc., and may be safe enough to allow regular (physical) play.
We'll see.