As much as I wanted to support Linux hardware vendors, economics (I'm retired.) led me to purchase this Lenovo ThinkBook 15 Gen 3 (AMD Ryzen 5 5500U) with 20GB RAM and a 500GB SSD drive.
After much thought and some trials I decided to go with Obarun as my main boot on this laptop. It was no light decision since I boot 30 different Linux distros (I have installed over 100 distros since 2000.) on my main 3 DR Intel i5 tower. I left 250GB to Windows and divided the other 250GB to 2 ext4 partitions: 70GB for "/" and 167.3GB to "/home"
I did not follow the Obarun pre-installation instructions of creating another esp partition. I wanted to use the drive's own SYSTEM_DRV vfat esp partition despite the fact that it was only 260MB. Even after copying over the 2 files from /boot I still had used only used 29% (74MB) of the partition.

- First I used a lsblk script to determine that the esp partition was nvme0n1p2 - It was the only vfat partition and it was labeled SYSTEM_DRV.
- Then I mounted that partition to /mnt/esp
- cp /boot/vmlinuz-linux /mnt/esp/
- cp /boot/initramfs-linux.img /mnt/esp
- sudo efibootmgr -c -d /dev/nvme0n1 -p 2 -L "Obarun" -l \vmlinuz-linux -u "root=LABEL=Obarun ro initrd=\initramfs-linux.img"

That was it. Thereafter the computer booted to Obarun.
The key points are the "-p 2" since the esp partition is on the 2nd partition NOT the 1rst and I labeled my "/" "Obarun" via e2label.

To boot Windows 11 Pro requires pressing F12 quickly as the computer is turned on or reboots.
When I read the subject I was expecting a story of an unsuccessful installation. Then I thought before I even read the message to comment that if you DO find a solution, please describe it here so the wiki can be updated.
And then I read and re-read the message. WOW!!

As far as I was able to discover, up to win7 MS used an MBR disk, then gradually made a shift where editions would come out stock as GPT and some upgraded machines somehow simulated/cheated UEFI to work on an MBR disk, so W10 on mbr disks are w10 upgrades of older systems, while W10 on uefi are most likely installed on an empty disk as W10. Then W11 comes out stating that it will not work on anything BUT GPT.

Most stock W10 installations I've seen from scratch create an /efi /boot partition on GPT as 100MB but using NTFS, not vfat/fat32. Then as far as I can tell linux (our linux at least) grub can not boot on ntfs.
Maybe Lenovo (purchaser of linux via rh/systemd) seems to be selling a non-standard MS installation so linux can be installed over W11.
The only other solution I see for people is to copy the contents of an NTFS /efi temporarily to another partition, format the partition to vfat/fat32 the copy the contents back and install refind/efi and a bootloader hook in it while using os-prober to pick up a W10/w11 boot entry in case it doesn't boot itself.

My preference (at work where I'm required to have this total shit of a system on the machine so I can access others' problems via weird gui sw that take over their desktops) is to have a separate 2nd disk where the efiboot exists for disk1 but bios will allow booting from 2nd disk optionally which is the faithful and secure mbr system.

Congratulations though, I wish I had more time and space to play with this till I can fully understand it, even though I reject it. I've never trusted this efi/uefi business since day 1.
In case it clarifies things:
Here's the lsblk of the 500GB SSD on this Levovo laptop.
Before you ask I don't know what the nvme0n1p1 partition is because it's format, if it is formatted, is unknown.

nvme0n1 476.9G
├─nvme0n1p1 16M
├─nvme0n1p2 vfat SYSTEM_DRV 260M
├─nvme0n1p3 ntfs WINRE_DRV 2G
├─nvme0n1p4 ntfs Windows-SSD 237.4G
├─nvme0n1p5 ext4 Obarun 70G / 6.8G 10%
└─nvme0n1p6 ext4 Home 167.3G /home 14.1G 9%

I was not that opposed to trying this because I'm an old-timer who still uses Legacy Grub on my MBR main tower. I preferred to tell the computer what I want to boot = menu.lst not have grub.cfg continually rewritten... And Grub 2 is still too stupid to use root=LABEL= on its own it ale=was rewrites to UUID or totally useles /dev/sd.

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