I have never used Wordpress, but I did see those image sizes, Wordpress does render your original image in differnt sizes, and interpolation might make slightly blurred images.
However. A bit late as well, meet friends for a beer in the afternoon.
Sticking with the svg Europe file from https://simplemaps.com/resources/svg-europe some hints.
You import a vector .svg like this, and because this comes with a transparent background, lock and fill like this little animation https://i.imgur.com/ayRWAeq.mp4
You can fill just a country or the whole map with a pattern or just a country by choosing a path. https://i.imgur.com/N4wdMFX.mp4
Then as an example, A layer under for the sea. Lock the transparency and fill all the land with color, Choose your country, fill with a pattern. https://i.imgur.com/3gyZnGn.mp4
All sorts of ways to mix fill and paths. Those little clips are a bit quick. I have some old patterns with transparent backgrounds, some attached, unzip and and put the folder in your patterns folder.
However. A bit late as well, meet friends for a beer in the afternoon.
Sticking with the svg Europe file from https://simplemaps.com/resources/svg-europe some hints.
You import a vector .svg like this, and because this comes with a transparent background, lock and fill like this little animation https://i.imgur.com/ayRWAeq.mp4
You can fill just a country or the whole map with a pattern or just a country by choosing a path. https://i.imgur.com/N4wdMFX.mp4
Then as an example, A layer under for the sea. Lock the transparency and fill all the land with color, Choose your country, fill with a pattern. https://i.imgur.com/3gyZnGn.mp4
All sorts of ways to mix fill and paths. Those little clips are a bit quick. I have some old patterns with transparent backgrounds, some attached, unzip and and put the folder in your patterns folder.