Yeah afaik there are a couple of suitable places for more hydropower but no plans for more due to, like you said, local environmental reasons.
That said, sweden is basically already completely “decarbonized” (if anything can really be decarbonized), we only have a reserve oil powerplant that runs for maybe a couple of days each year (~9 days last year, though last year was especially bad). Sweden also generally has a pretty big net surplus (usually about 10-20% of production) of green power that is sold to the european grid.
It really is an almost impossible situation. The far right will win this one regardless what the government does. If they do nothing we will probably see some form of terrorism sooner or later, if they clamp down on it they will prove the activists right in that the government will reduce freedom of speech just because some muslims cant behave.
Maybe theres some way to eke out a win but I cant see it.