From this URL, we remove the sidebar, and full-screen screenshot to this local PNG file, then georef from the url
https://tasmap.org/#9/-42.8830/147.0026
The file read here with rast() can be read directly with this, or itis attached below.
r <- rast("/vsicurl/https://private-user-images.githubusercontent.com/4107631/479547609-2127f648-d117-457b-ba01-6b181cdd5843.png?jwt=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.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.0TjLYya2nBjCNiO9po3uqGNK47gdW9b9x1JJPAiipXM")
## this URL and this screenshot are intimately tied, I screenshot at full screen with sidebar removed (title bar is 50 pixels, which we subtract below)
url <- "https://tasmap.org/#9/-42.8830/147.0026"
r <- terra::rast("2025-08-19 23_53_47-TasMap.org.png")
r <- terra::flip(r, "vertical")
## drop the top 50 rows (before we set the extent)
r <- terra::crop(r, terra::ext(0, ncol(r), 0, nrow(r) - 50))
tx <- strsplit(url, "/")
z <- as.integer(gsub("#", "", tx[[1]][[4]]))
ll <- matrix(as.numeric(unlist(tx[[1]][6:5])), ncol = 2)
crs <- "EPSG:3857"
## this is the centre point
xy <- terra::project(ll, to = crs, from = "EPSG:4326")
## this is the number of pixels
dm <- dim(r)[2:1]
## zero scale
z0 <- 20037508 * 2 / 256
## so width,height of image is
wh <- dm * z0 / (2^z)
## so extent of it is
ex <- rep(xy, each = 2L) + c(-1, 1, -1, 1) * rep(wh, each = 2L)/2
terra::ext(r) <- terra::ext(ex)
terra::crs(r) <- crs
plotRGB(r, asp = 1)
m <- do.call(cbind, maps::map(plot = F)[1:2])
lines(project(m, to = crs, from = "EPSG:4326"), lwd = 4, col = "firebrick")
Ok, listmap doesn't have an explicit url, but you can search for lat,long and then just hit the zoom level on the interface, and then it's exactly the same as the tasmap.org, so I got the layer I wanted: