I tried to install Ubuntu 20.04 in my Dell G5 which has 2 drives. One with Windows 10 on it (256 GB) and another one with 1 TB capacity.
I shrunk the volume of 1 TB by 150 GB and tried to install there.
But Ubuntu installer didn't allow me as I got a dialog after the Keyboard setting said "Turn Off RST" with the message
This computer uses Intel RST (Rapid Storage Technology). You need to turn off RST before installing Ubuntu. For instructions, open this page: help.ubuntu.com/rst
If I make any changes in the BIOS setting, like changing the Intel controller from RAID to AHCI, Windows won't boot and goes into System Recovery.
I didn't have this issue when installing 18.04. While creating the partitions, you need to create a EFI partition with 200 - 500 MB with the usual steps and the installation will be completed succesfully.
On restarting, you will not be getting the GRUB but instead Ubuntu will boot by default. If you need to boot Windows, you will have to go to the BIOS and choose from the UEFI boot option each time.
Once 18.04 installation is complete, you can upgrade it to 20.04.
After upgrading I installed the KDE desktop and at the login screen I chose the "Ubuntu on Wayland" option.
After doing these 2 things, I lost the new features of 20.04 like the Ubuntu boot screen with Dell logo and the power off/log out blur effect screen. Not sure how to get that back.