I've been running Pop!OS on my Surface Pro 6 (i7-8650U) for a while now (with the linux-surface kernel!), and touch/pen support is relatively good; only weird thing is the limitation around what the pen can do; e.g. you can touch-scroll with your fingers (and other gestures) but you can't use the pen to scroll; the pen behaves more like a mouse, e.g. it will highlight text instead of moving the page (which makes sense)

You shouldn't have any issues with installing the base OS; the keyboard cover should just work; but pen/touch doesn't work out of the box, so to get that you will need the linux-surface kernel. I use the Debian package repository (as Pop!OS is a Debian or Ubuntu derivative - they use the same packaging system). Note that you will also likely want to tell the package manager to "hold" the installation of the non-surface kernel, using apt-mark hold. You'll probably want to hold linux-headers-generic and linux-generic. (I think I have particular versions held as well.)

I quite like to use the "Xournal++" app for touch/pen friendly writing/drawing, and have also used it for signing PDFs (though only the visual type of signature, not the digital type like Adobe does).