As a second step we could also maybe offer an admin UI in the same flavor as the one for the autocomplete.
Yes. Or better, modify the existing Autocomplete page to have options for both?
BTW, the AutoComplete page is very confusing. I still do not understand what “Push Settings” does, nor how it compares to the “Save” button. Reindex at least makes sense. Maybe some help text on that page to better describe how it works? And/or consider different button names that might be clearer?
Regarding the merging of categories/tags/posts for the dedicated search results page, this is also not easy to realize given that InstantSearch.js generally expects you to have a unique “type of content” that you can filter on.
Minimally you could allow categories and tags and any other taxonomy terms to be merged. Just like you have “All Posts” you could have “All Terms.” And then allow for ways to limit the taxonomies included. I would be happy with a hook for that.
Frankly, I would be happiest if you could allow me to override the entire configuration page and just hardcode the configuration so I can commit to version control as well as continuous integration testing and deployment.
Maybe you should consider extracting the essence of the plugin and integrated a custom version of the plugin.
We did not have the time budgeted for this. Algolia was an 11th hour switch from Google Custom Search, and other than these issues we are really glad we switched. I can envision wanting to use this for other clients whenever possible.
What would be great would be if, instead of proposing I fork and modify your plugin if we could collectively explore ways to make your plugin extensible via hooks so that your plugin is always the base people start from?