I think you will find enough options.
Cabanillas is open, but you must call ahead to set up entry. There are two pensiones in La Robla, and the RR workers that filled up the places in the fall are gone. Two pensiones in Pola de Gordón, and 15 de mayo does reservations via whatapp.
Albergue in Poladura is open, and the Posada de Embrujo serves meals but hasn’t yet opened. Pajares has both a pensión (above the bar/restaurante Mirador) and a casa rural.
Sandra’s place in Bendueños, which is WONDERFUL, is open, but you should call ahead.
Albergue in Llanos de Somerón has been open since April 1.
Pola de Lena has several places to stay, but I think the albergue is still closed.
Mieres “albergue” (in a university dorm) is open and looks fine.
Closed — albergues in La Robla, Buiza, and Pajares.
As someone pointed out, if you want to walk the Salvador in 4 days, the first day you will have to walk 38 to get to Pola de Gordón. I had done that three times without problems, but last fall found that I was really zonked when I got there. Maybe it had something to do with turning 70. I hope to walk the Salvador again, and will do it in five days this time.
Alvaro Lazaga just finished the Salvador and has some youtubes with a lot of joviality in the snow. But totally passable.