Thanks for the suggestion! Adding support for Sia is probably possible.
That said, please note that S3QL is a fully volunteer driven project. This means that new features and bugfixes are implemented only when someone has a personal interest in them and therefore also does the necessary work (and I am not personally interested in Sia). Posting ideas is therefore generally unlikely to result in the feature being implemented.
Would you be interested in working on this? If not, I will close this issue in a few days (since the purpose of the issue tracker is to coordinate ongoing and planned work, rather than enumerate all the work that could possibly be done).