Scrolling with the trackpad is continuous and smooth in Terminal.app. On macOS I often prefer to cat files and then scroll them myself because of how nice it feels - and how much direct control I feel like I have over the scrolling position.
I wish it worked with man pages, vim and less. But that sounds like a hard problem.
(Same in iTerm2. In Linux, Terminator can scroll to partial lines, but output is instant, so it doesn't have the effect the OP is looking for.)