@xoron no, SH software does not need to be hard to set up
I wouldn't call it SH here, for the same reason as, like, Angry Birds. It's a #LocalFirst app, but when it does interact with a server (In your case, just for updates), it is someone else's server. If that service worker cache becomes unavailable, and if that server is down, you're out of luck.
If you offered it as a .mhtml file, or a binary that just ran a local file server, that would put it over the edge for me