I’m using EndeavourOS with Plasma on a Thinkpad L13 Yoga G4. A recent update fixed the ACPI message SW_TABLET_MODE, so now the device automatically disables the keyboard after a couple seconds of being flipped, and plasma switches to tablet mode automatically. From there, everything works with zero problems. I use it to take notes in uni and switch often from normal laptop work to tablet mode for note taking.
I didn’t notice exactly when it was fixed, but since I bought it and until some time ago there was a problem with I think an I2C device that prevented the switch, and I had to use a set of cobbled together scripts to manually do it
No significant input lag, i use Xournal++ and in one semester for a single course i tend to make a single file of 120+ pages.
I use the integrated pen, which also slots into the chassis to recharge, but other pens that use the same wacom protocol also work, i use an HP one alongside the integrated one from time to time