Query for Lightswitch in GraphQL
Just saw this resolved issue on GitHub: https://github.com/craftcms/cms/issues/5930
So Lightswitch querying should be fixed in the upcoming release CraftCMS 3.5

Edit: there is a workaround until 3.5 is released. see comment by @harrymee123 and my example query at https://github.com/craftcms/cms/issues/5930#issuecomment-657417173