Not sure if you think this fits into effectsize, but I'm missing convenient wrappers around common significance tests, including options to use weights. I have done this for now in sjstats:
https://strengejacke.github.io/sjstats/reference/index.html#summary-statistics-and-tests (e.g. https://strengejacke.github.io/sjstats/reference/chi_squared_test.html).

Let me know what you think. The functions are more or less in easystats style, so would be easy to move over here.