It’s useful for the ~.4% of browsers that will execute a module script without checking its integrity. But I do indeed intend to put more emphasis on SRI in the future.
One thing you may have meant by "serverless" is that you don't use a database / don't collect data on users. This is another angle you might want to use to highlight the safety of using your service.
What if someone modifies not only the script, but also integrity hashes in snippets on your site?
Defacing capability can be used to change the integrity hash—how it appears to the users (other developers) in snippets—to match maliciously modified script, making it trusted.
End developers using this library would thus, at their own accord, include URL to altered script and its hash in their pages by copy-pasting a snippet from the defaced landing page, satisfying browser integrity checks.
A subtle change like that is unlikely to be noticed by end developers, who would have to count on library site maintainers to have mechanisms in place to notice such an attack promptly and (perhaps more importantly) to not suppress the news about the incident.