KDE Neon is my prefered KDE based distro.

For the installation on my Thinkpad E15 Gen 2, I used the latest image (neon-user-20200910-0945 at that time).

The image is running a 5.4 kernel and the amdgpu is not correctly managed, so I needed to boot in safe graphics mode.

After installation I downloaded the latest stable kernel (5.8.8-050808-generic) from here with the following files

https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.8.8/amd64/linux-headers-5.8.8-050808_5.8.8-050808.202009091435_all.deb

https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.8.8/amd64/linux-image-unsigned-5.8.8-050808-generic_5.8.8-050808.202009091435_amd64.deb

https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.8.8/amd64/linux-modules-5.8.8-050808-generic_5.8.8-050808.202009091435_amd64.deb

and installed the packages:

cd Downloads/
sudo dpkg -i *.deb

My laptop has a bug related to Fn keys not working without go to sleep mode (related to a BIOS problem see here https://www.virtualconfusion.net/thinkpad-e15-g2-and-linux/).

But current setup prevent my laptop to come out from sleep mode.

I needed to remove the nomodeset from the kernel options. This is not part of the default grub file in KDE Neon.

The nomodeset is added via the file /etc/default/grub.d/neon-installation-nomodeset.cfg

GRUB_CMDLINE_LINUX_DEFAULT="${GRUB_CMDLINE_LINUX_DEFAULT} nomodeset"

whether I remove the file or remove the nomodeset options.

I just simply renamed the file:

sudo mv /etc/default/grub.d/neon-installation-nomodeset.cfg /etc/default/grub.d/neon-installation-nomodeset.cfg.old

Then update the grub configuration:

sudo update-grub

After reboot I am able to put my computer in sleep mode and get out of it and the Fn keys are working