Not familiar with GDevelop but I found this on google:
"If you want all your objects to be sharp instead of blurry, and you don´t want to uncheck everything (is tedious), Go to Project, game settings, properties and then in the scale mode select "Nearest (no antialiasing, good for pixel perfect games). With that done, every single object is going to look sharp."
For Unity set the Filter Mode on the assets to "Point (No Filter)" and maybe uncheck "Generate Mip Maps".