I found this technique last night, and made an account here to share it as I've seen several people looking for a solution.

First of all, after you have exported your map, make sure to place it where it would be on your globe in terms of latitude. In my case, I knew where the equator was, and how far north a certain point was, so I measured out where the map would be, ending up with this (remember that the image has to be 2:1 for this to work):

1KrA87A.png

Then, I turned on grids, making sure it was divided into 20 squares top to bottom, 40 side to side, and put down guidelines in order to divide the map into equal parts in height. This is how it looks:

8A5pzj7.png

Make sure that you cut out your landmass from the rest of the map, and use a colored background (this becomes important later), in my case I placed my landmass near the center of the extracted piece, so that I was only working on the part I wanted to adjust, so this is what I was working with:

nILMc0N.png

Next, make sure to cut out every horizontal segment, ending up with as many layers as your landmass covers. My landmass was 9 segments tall from the horizon, and I added a 10th layer to be able to properly adjust it later. With the guidelines in place, it will make sure that you get a precise cut for each layer. Press ctrl+x to take out the segment, and shift+ctrl+v to place it back in the same location. This is what it should look like (I marked my layers with 1-9 from the equator to make it easier):
5p0MrGa.png

Now, I asked ChatGPT to do my calculations for me, to see how far I would need to adjust each layer in width in order to make it project correctly on a globe. In this case, the length is taken from the line closest to the equator, so for instance for the segment number 5, it would be the percentage wide on the line between the 4th and 5th line from the equator:

WLOX96N.png

If you want, you can make it even more accurate by doing it in more segments, but for this tutorial, 10 lines is more than enough. If you want to be more accurate you can cut it into 40 segments, then use this table:

xyc7efm.png

Next, you need to adjust each map segment to the proper width. so select each segment, and then input the percentage on the table above into the "w" adjustment bar on the top:

0ynw79X.png

After you have adjusted each bar you will end up with something like this:

hx5aPYc.png

Now, starting from the bottom, you select the 1st layer, and go into edit -> transform -> perspective:

i0O3bjj.png

then, you adjust the top line of the first layer to align with the second layer, and then the second to third, and so on:

NJUeAJI.png

When you are done, you should have something like this:

cbvP805.png

And you're done! you can now fill in the background with black, and import the heightmap into your mapmaking software, like wonderdraft, and it will now be properly aligned and will look good on a globe. If you want to remove the black, you can either put an ocean background behind the layer of the map and change the blend mode to screen, or you can select the black color, then select -> similar, and then delete the black parts. If you use a transparent version of the map it will take some extra work to align it correctly when using the perspective tool, the black background is there to make it easier. You can also use a background of the same color that you are going to use for your ocean to make it even easier.

Here's how my planet looks with the adjusted map (added some colors and clouds as well):

ZZs268E.png

If you have several continents, you can do this process for each of the continents, and then put them all together on a big map, as long as it is 2:1 in dimensions, and as long as the continents are on the correct latitudes.

I hope this can help you modify your map if you want to project them on a globe. If you have any questions about this process, feel free to comment!