Yeah, as far as I know, if the game is blacked out locally, its blacked out on both the local broadcast and Sunday Ticket. There was a big stink a few years back because local bars were streaming the game from the web and the NFL sent C&D letters threatening legal action.
https://stopchargerblackouts.org/
They were about 10k short at the deadline this week.
Its really surprising, as I think there's a pretty strong fandom for the Chargers here, but I guess that just doesn't translate to ticket sales. No wonder they've kept Turner and Smith for so long, no reason to put a better team on the field.
As long as I live in SD though, I'll go to the game though.... every 8 years when the Bears come here.
Still, not as bad as going to a Padres game though. I've never been to one where at least half the crowd wasn't rooting for the visiting team.