A working QEMU configuration to try the tutorial

Let's install the required packages for this to work:

pacman -S qemu swtpm

You will also need to download the OVMF bios files from the Fedora website as the one in the Arch repo are broken and will hang at boot, just pick the first one then click on Builds, pick the only result then download a file that should match the name of edk2-ovmf (it should be under noarch).
Open and extract the RPM file that you downloaded and copy OVMF_CODE.secboot.fd and OVMF_VARS.secboot.fd (you'll find them both in the archive) into your VM folder that you'll create below.

Create a folder for your VM files:

mkdir myVM
then myVM

Download and move the Arch Linus ISO into this folder.

We'll create a swtpm socket so we can setup a TPM inside the VM.
First, create a folder by the name of tpm:

mkdir tpm

Then create and open the socket:

swtpm socket --tpm2 --tpmstate dir=tpm --ctrl type=unixio,path=tpm/swtpm-sock

Note: the swtpm process will close everytime the QEMU VM will shutdown, forcing you to restart it everytime.
Note2: you may encounter an issue with the TPM if you try to follow the instructions 7b where the partition will not unlock. To fix this problem, just fully shut down the VM then restart it, for some reasons, the secret you may add to the TPM will not be available until the next full VM reboot.

Let's create the QEMU disk images:

qemu-img create myDisk.img 16G
qemu-img create EfiTool.img 100M

You may now boot the VM:

qemu-system-x86_64 --enable-kvm -m 2048 \
	-drive if=pflash,format=raw,unit=0,file=OVMF_CODE.secboot.fd,readonly=on \
	-drive if=pflash,format=raw,unit=1,file=OVMF_VARS.secboot.fd \
	-vga virtio -machine pc-q35-2.5 \
	-net user,hostfwd=tcp::10022-:22 -net nic \
	-cdrom archlinux-202x.xx.xx-x86_64.iso \
	-drive file=myDisk.img,format=raw,index=0,media=disk \
	-drive file=EfiTool.img,format=raw,index=1,media=disk \
	-chardev socket,id=chrtpm,path=tpm/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm \
	-device tpm-tis,tpmdev=tpm0

Note: change the Arch Linux ISO name to whatever you downloaded.

On the booted VM, start the sshd service and change the root password:

systemctl start sshd
passwd

Now login on your VM:

$ ssh localhost -p10022

You may now proceed to follow the tutorial.

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Once you reached the step 6b, we will create a new FAT32 file system stored on the EfiTool.img disk so we can enroll the keys.

Open a terminal and type gdisk /dev/sdb (it should be sdb).

Type all these commands in this very specific order to create a 100M EFI partition on the sdb device:

o (create a new GUID partition table)
y (confirm the disk erasing)
n (create a new partition)
[Enter] (pick the default option)
0 (try to use the very first available sector)
[Enter] (pick the default option which is the last available sector on the disk)
ef00 (the code that correspond to the EFI System Partition partition type)
w (write the changes to the disk)
y (confirm the changes)

Now create a FAT32 partition on the disk:

mkfs.fat -F32 /dev/sdb1

Mount it in a temporary folder:

mkdir /tmp/efitool
mount /dev/sdb1 /tmp/efitool

Then move the auth files and the EfiTool.efi binary:

cd /root/secureboot_keys; cp *.auth /tmp/efitool
mkdir -p /tmp/efitool/EFI/BOOT
cp /usr/share/efitools/efi/KeyTool.efi /tmp/efitool/EFI/BOOT/BOOTX64.EFI

Unmount and delete the temporary folder:

unmount /dev/sdb1
rmdir /tmp/efitool

You may carry on with the tutorial as usual now.