An example of how to directly warp a geoid model into R.

geoid_warp_EGM2008.R

# Warp and plot the EGM2008 1' geoid model
# geoid COGS hosted here: https://www.agisoft.com/downloads/geoids/

library(vapour)
library(gdalio)
library(terra)
source(system.file("raster_format/raster_format.codeR", package = "gdalio", mustWork = TRUE))

geoid <- '/vsicurl/https://s3-eu-west-1.amazonaws.com/download.agisoft.com/gtg/us_nga_egm2008_1.tif'

ri <- vapour_raster_info(geoid)

gdalio_set_default_grid(extent=ri$extent,
                        dimension = ri$dimXY,
                        projection = ri$projection)

geoid_ras <- gdalio_terra(geoid)
plot(geoid_ras, col=scico::scico(255), axes=FALSE)