Here is another code to mimick the visual that you show.

ggplot(data=test)  
    statebins:::geom_rrect(data=test, mapping=aes(xmin=1, xmax=2, ymin=1, ymax=2), 
                           fill = '#d0e1e1', 
                           color=NA, alpha=0.7)  
    statebins:::geom_rrect(data=test %>% 
                               dplyr::filter(!is.na(value)),
                                             mapping=aes(xmin=1, xmax=2, ymin=1, ymax=2, fill =  value), 
              color=NA, alpha=1)  
    geom_text(data=test, aes(x = 1.5, y = 1.5, label = state))  
    # annotate("text", x=1.5, y=1.5, label= state)  
    facet_geo(~state, grid="ch_cantons_grid2")  
    scale_fill_gradient(low = "#dccbd7", high = '#564364', name = "Label value")  
    theme_minimal()   
    guides(fill = guide_legend(title.position = "top"))  
    theme(legend.position = c(0.2, 0.95), 
          legend.direction="horizontal")  
    theme(axis.title.x=element_blank(),
          axis.text.x=element_blank(),
          axis.ticks.x=element_blank(),
          axis.title.y=element_blank(),
          axis.text.y=element_blank(),
          axis.ticks.y=element_blank(),
          strip.placement = "bottom",
          plot.title = element_text(hjust = 5),
          strip.background = element_blank(),
          strip.text.x = element_blank(), 
          line = element_blank())

You can change guides(fill = guide_legend(title.position = "top")) by guides(fill = guide_colorbar(title.position = "top")) to have continuous color scale.