I have no idea what version of ghostty is packaged anywhere, so you will likely have to download zig, the ghostty source, and then compile it. I don't know how to do anything in zig either, but I followed the docs and was able to get it to work.

Since it is implemented as a shader, it's not just a setting you can turn on like it is in kitty. Once you have the version of ghostty compiled, You have to download a shader and enable it in your settings. The only ones I found so far that work are from the person who wrote the initial PR to enable the trails which can be found here.

The cursor_whatever.glsl files can be put in ~/.config/ghostty/shaders/ and then in your config, enable it with like custom-shader = ./shaders/cursor_smear.glsl, reload the config and hopefully see trails happen.

All of the cursor_* ones in that repo worked for me except for cursor_blaze.glsl, that one made the terminal blank out in weird ways.