As someone who also built their site on cargo(2), but barely knows any code, chatgpt/claude was super helpful for me when it came to customization. I added a bunch of custom transitions/fxs for certain pages, custom cursor, etc - simply by feeding chatgpt my css/html per page, telling it what i wanted to happen, and asking it to rewrite the code in order to achieve the desired effect. then all that was left to do was copy and replace the code that cargo already had saved.
http://magnusholm.es/ (view on desktop to see the stuff im talking about, i removed it all for the mobile vers)