Yes, SPARQL patches do work. You can use rdflib’s updater which uses rdflib statement objects, or you can use Solid File Client’s patch method. The docs for Solid-File-Client show the basic syntax of two different kinds of patches - ‘text/n3’ or 'application/sparql. You could also use those examples with straight fetches with only an auth library and without Solid-File-Client.
The text/n3 form of patch is more flexible and will be the format of patch that is standardized in the Solid spec.
Both forms of patch work on NSS. If you try them on other platforms, you might report back here.