How can I galvanically isolate 5V 1A DC power?
What kind of dc-dc converter isolates galvanically?


Pretty much +90% of them. 

If I look in Farnell I see there are 5640 isolating types and about 400 non-isolating types: -



Common Suppliers: Traco_Power, XP Power, Murata, Artesyn, Recom, TDK_Lambda