Just wondering if we can use Bandcamp as our song demo link?
Hmmm, I think I just answered my own question by trying it! And it seems to work. You just go to the song page in Bandcamp, copy the URL (ex. https://radiopossum.bandcamp.com/track/lets-go-eat-garbage-cross-roads-and-poop) and then paste that into the Demo URL field on the new song page. Then, when someone clicks the link on your song it takes them to your song's Bandcamp page.
As you say, it just provides a link which takes you to the Bandcamp song page.
Bandcamp doesn't integrate as well as Soundcloud. With Soundcloud it will actually embed the player in your song's page but Bandcamp won't do that.