Upgrade to macOS Big Sur

Requirements

For the installation you'll need a few things:

At least 12GB USB drive
A Mac, a Hackintosh, or a VM running macOS to create the installation media
The Big Sur EFI folder from the repository

Download the installer

Download the gibMacOs tool and open gibMacOS.command:

Hit M to change Max macOS and then enter 10.16 to change the catalog to the one containing the Big Sur Installer.

Hit C and than choose 4 to change to the developer catalog.

Select the number which says Big Sur and hit enter to download it.

After it finished downloading open the InstallAssistant.pkg file that was downloaded. It's located in gibMacOS/macOS Downloads/developer/XXX-XXXXX - Install macOS Beta folder. This package will create the Install macOS Big Sur Beta.app in /Applications folder.

Once it's done you should find your installer located in the /Applications folder:

Create the installation media

Open Disk Utility and format your USB Drive as the following:

Name: MyVolume
Format: macOS Journaled
Scheme: GUID Partition Map

Once it finished formatting, open Terminal and type in:

sudo /Applications/Install\ macOS\ Big\ Sur\ Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

This will take around 10 minutes, so sit back and relax...

Put EFI folder for installing macOS

For the last step before booting, you should put new Big Sur compatible EFI in EFI folder for USB-pen installation.

Mount your EFI partition for USB-pen
Place unzipped file on your EFI folder
You can edit the config.plist and fill out the SMBios section

And now, after you done with everything, restart the computer and boot from Install macOS Beta (external)
From now on this will be the same process as it was before. The installation will take around an hour.

As stated in Dortania's Big Sur Guide if the installation stuck at Forcing CS_RUNTIME for entitlement DON'T RESTART YOUR COMPUTER it's totally normal!: ~~in my case I don't report a similar issue!~~ present upgrading from Beta 4 to Beta 5

Put EFI folder for booting macOS

After successful installation, before booting your system, you should put new Big Sur compatible EFI in EFI folder for your disk.

Mount your EFI partition
Place unzipped file on your EFI partition
You can edit the config.plist and fill out the SMBios section

This is a screenshot from macOS Big Sur Beta 4 - 20 August 2020

What is Different from Catalina

Beta 4 installed on 20 August 2020

Almost everything is the same in case of functionality.
~~What's not working at the moment~~
- ~~Battery indicator~~ Battery fixed
- ~~Ambient Light Sensor Device~~ Ambient Light Sensor fixed

Beta 5 installed on 22 August 2020