Not galvanized- bare steel. Your shotgun is a Stevens Model 94B. In better days, it looked like this:
These were utility grade shotguns- their value is not as a collectible, but as a shooter, so any restoration work you do will not hurt any values.
Start by removing the wood, and the barrel. You can clean up the reciever with light oil and a COPPER pot scrubber, followed by a rubdown with more light oil and a soft cloth.
Bluing is gone from the barrel- may have been removed by someone else. You can clean it up, and try a home bluing, or get a smith to blue it for you.
To polish up the barrel, use wet-r-dry sandpaper, and a little oil. Would probably start with 220 grit, going lengthwise, then 400 grit used like a shoe shine rag around the barrel. Remove all oil after polishing (take it outside, spray with brake cleaner, do not touch metal with bare hands after degreasing) Warm barrel with hair dryer, apply Oxpho Bluing with a clean cotton ball (not steel wool).
OR there are spay paint type finishes like Cerakote made for guns that you bake on. Still need to clean metal up first. Howver, the product will cost you more than the gun is worth.