Well there is a download link to the Nexus 5 port in its current state over at xda if you go into Nexus 5 General -> jolla developer ports sailfish os to nexus 5, then go to the bottom of page 6, but that is now an older version of the sailfish OS, although the latest sources seem to be available to update the rom, I'm not sure how to build it.

If someone has instructions to build the sailfish rom, then it would be greatly appreciated, since this is my first post, I doubt that I can post links otherwise, I would have given you a direct link to the nexus 5 sailfish os rom, the github account of where to build, and a link to the modified kickstarter file that I made (based from the one found in the github repo, to build the latest version for the nexus 5.