I’ve owned a Thinkpad A485 with touchscreen for years and had several Linux distros on it including Manjaro and Linux Mint which I am currently using.
Never had any issues, touchscreen always works out of the box without me having to do anything extra. In fact, with a few distros, I’ve had issues with certain wireless mice, but my touchscreen always has worked. So I’ve actually had slightly better luck with the laptop touchscreen than some external mice lol.
Now a qualifier: I rarely use the touchscreen, and when I do, it’s always just to click something or scroll on an article or file list. I don’t do any special gestures or fancy touch functions, so I can’t speak to support from that perspective.