Hello, is there a way to make the default padding smaller on desktop? For example: FloatingActionButton has the correct padding for mobile, but I want the button to be smaller on desktop, is there a local I can override?

Unfortunately no.

As far as I understand, it's the deep consequence of having originally targeted touch screens. I have seen some proposed workarounds, but I haven't tried any of them.

FAB is a material design thing and it specifies the amount of padding in the spec. The material library is sometimes very opinionated. Having a FAB on desktop can look out of place. Google recommends putting them in a navigation rail for large screens: https://m3.material.io/components/floating-action-button/guidelines#34a9762a-b855-465d-9263-650b81a05f42