I made this in 2022 in QGIS (but when I uploaded it on Reddit back then, you may find it as starting at Ste-Helena island.... don't ask me why, I don't remember how I made that mistake when posting it)
Westphalian borders in the sense of the Westphalian states. Aka, each of the countries ends at a defined and demarcated line instead of areas of influences. You could think of it as “modern borders”. I don't know if the term is also used in English, but last time I posted it (on Reddit) nobody questioned it, asked about that part, I learnt it at the university in my geography course.
I used to makes a lot of maps like this or using a GIS of variable quality, interest and end result. Also, I didn't check if I made some spelling / grammatical mistakes back then on this one, but since the word count is low it should be fine, even if I messed up with fewer.
I made this map in 2022 using paint.net
You do the same with this website (https://minecraft.ign.fr/) to a 5x5km area at most. It's a French service, it works for Wallonia too. And you should be able to export the rest of the world by changing the source to OSM, but I never tried that.