I used Virtual Reality Kneeboard with an old Wacom digitizer/tablet for quite a while.
Eventually though, VRK stopped being updated and I switched to a G2 from the Rift S. Open knee board has been my go to ever since. Once it’s set up it usually works great. You can add pdfs or checklists, it even picks up the kneeboards in DCS mission files and will display those. Once my old Wacom tablet died. I picked up an Intuos S with Bluetooth at a Best Buy when it was on sale. I turned it 90degrees and velcroed it to an old Sporty’s kneeboard. It’s been a solid addition to my VR setup. I almost never use the built in DCS kneeboard anymore.