The startup script is simply startup.m in whatever folder MATLAB start with.

Now how about Python? For plain Python (anything that you launch in command line, NOT Spyder though), you’ll need to ADD a new environment variable PYTHONSTARTUP to point to your startup script (same drill for Windows and Linux).

For Spyder, it’s Tools>Preferences>IPython console>Startup>”Run a file”:

but you don’t need that if you already have new environment variable PYTHONSTARTUP correctly setup.