So I went and bought a Galaxy Tab S2 model SM-T813 the other day. Happy to report that /e/ builds cleanly 9.0 Pie for this device. I installed the image and have been playing with it all day, and I’m quite happy with it. Will definitely be sticking with /e/ on this tablet.
No glaring bugs that I noticed. The home screen icons are all a bit small for the tablet sized display, I wish there was a way to resize the icons to something larger. Also some of the default apps are not really appropriate for a tablet like this, but it doesn’t cause any problem. For example, there is no GPS on this tablet, so the Maps app isn’t too useful. Text Message app also not useful on this device. That’s about it, smallish icons and inappropriate tablet apps are really the biggest issue I could find, certainly not a blocker for using /e/ on this great little tablet.
FWIW I did not have to perform any bootloader/firmware update as @ecs mentioned. I simply followed the installation steps outlined here, using heimdall and adb. I did however install all outstanding updates on the stock Samsung Android OS before installing /e/, so perhaps that performed the firmware update for me?
Here’s a link to download my unofficial build. This is /e/ 9.0 Pie, and includes the March 2020 security patches.