Thanks @zeileis. I believe that I've managed to plug those two cases now:

pkgload::load_all("~/Documents/Projects/tinyplot_vincent/")
#> ℹ Loading tinyplot
set.seed(0)
d <- data.frame(y = rep(1:4, each = 100), x = c(
  rnorm(100, mean = 5, sd = 2),
  rnorm(100, mean = 2, sd = 1),
  rnorm(100, mean = 8, sd = 1),
  rnorm(50, mean = 1, sd = 0.5), rnorm(50, mean = 9, sd = 0.5)
))
tinyplot(y ~ x, data = d, type = type_ridge(bw = 0.5, gradient = TRUE, breaks = -1:6 * 2))

tinyplot(y ~ x, data = d, type = type_ridge(bw = 0.5, breaks = -1:6 * 2))

Bonus: Replicating a fun example from the ggridges package/vignette. Note that this is a case where grid = TRUE gives misaligned horizontal lines (due do the y-axis scaling?). But we can deploy draw as a workaround. (Something to think about fixing. Maybe part of a dedicated tinytheme("ridges") theme that also does things like removing the y-axis label?)

data(lincoln_weather, package = "ggridges")
op = tpar(las = 1, mgp = c(3, 0, 0))
tinyplot(
  Month ~ `Max Temperature [F]`, data = lincoln_weather,
  type = type_ridge(gradient = "plasma", scale = 3),
  # grid = grid(nx = NA, ny = 12),
  draw = abline(h = 0:11, col = "lightgray"),
  axes = "l",
  main = "Temperatures in Lincoln NE",
  ylab = NA
)

tpar(op)

^{Created on 2024-11-22 with reprex v2.1.1}