I'm going to reiterate something that's probably already been said. Maybe not.
You SHOULD have the ability after POST to select the boot device. If not, you should have an option in the BIOS under some section where you Save and Exit. If you have that section in BIOS, Save and Exit, then there should be a grouping there with boot devices that the BIOS has recognized. Navigate to the boot device you want, then press enter. It should boot to that device.
I don't have a laptop so I can't deal with "should"s. Therefore I'm not going to get drawn into this other than this comment.
Next, installing Linux first is something I had problems with. Next, installing two OSs on the same disk is something I've had problems with. I don't CARE about "should" here, I am only giving my experience in dealing with dual boot systems.
So here is the part where whether you like it or not, it works well. Install Win11 on its own disk. This should be the only disk in your system when you do the install.
IF you have the ability to select boot device after POST, THEN REMOVE disk after all the install/updates are done. In another available space for disk install Ubuntu on that disk. This will prevent Linux from creating a Grub file on the Windows 11 disk.
This of course requires that you can install an OS from a USB to do the install of Ubuntu.
An OTHER option is to dual boot off of a single disk, which still requires you can load an OS from USB. Install Win11 first, not second, on the first disk partition. Don't do anything with a 2nd partition. Leave whatever amount of disk space you want for Ubuntu without a partition. Once install.updates are done you can probably run the Ubuntu install from Win11, but I'm not positive. If not you once again need to be able to boot from USB to load Ubuntu. During the install of Ubuntu, go ahead and boot into Ubuntu on the USB and do the install from the Ubuntu environment.
When installing Ubuntu it should ask if you are installing alongside Win11 and you would say yes. It should then show you the disk free space and you would select that free space, and here is the part that gets messy. Linux and Ubuntu need certain partitions and when I did an install with 22.04 it didn't do the automatic creation of partitions correctly.
If when you installed Win11 it created a small partition at the head of the disk which is an EFI partition then you are mostly good. There are different thoughts about installing to a single partition or multiple, I prefer multiple. I want a separate root (EXT4), home (EXT4) and SWAP space. Since you have such a small amount of memory, I'd make that SWAP space big, like 32GB big. This assumes you multi-task with Ubuntu. If you only do one thing at a time then the SWAP space can be smaller. So if you were loading Ubuntu to its own disk, you would first wipe out all partitions, you would also make sure the disk was initialized GPT not MBR. The first partition is the EFI, next is root, next is home, next is the swap. You can go to Youtube and get an idea about the sizes for each of these. EFI is FAT32. You COULD put the swap space on the disk following root so when you create home you can simply use the rest of the disk.
IF you do a dual boot single disk then a GRUB loader should have been installed in that EFI partition. It should have been created with the options to boot with either Win11 or Ubuntu. After POST, the GRUB loader will appear so you don't have to go into BIOS to select a boot device.
You CAN install Ubuntu with the Win11 disk installed. There should be a small EFI partition at the beginning of the Win11 disk. If there isn't, then your Win11 disk isn't set up correctly. It could be it's not initialized using a GPT partition. You need that EFI partition for the GRUB loader to be installed on. If you choose to install Ubuntu without the Win11 disk installed, the GRUB loader will be installed on the Ubuntu disk. This is my preference, but I can use a hot key to bring up boot devices at the end of POST.
After installing Ubuntu, go into DISKS tool, select the Win11 disk/partition and enable the setting that allows you to make settings you want, and then disable mount at startup, disable it from being visible.
So there's a long list of issues in what I said. One main point is disks need to be initialized with a GPT partition. Other main point is an EFI partition needs to exist, and it's FAT32. Other main point is if you don't have an option to select a boot device after POST is finished (strange, but OK) then your options are to go into BIOS whenever you boot to a secondary boot device, OR your install order/method should ensure that a GRUB file gets written correctly and the best way I know of making that happen is installing Win first, Ubuntu 2nd.
Your UEFI is not a problem. UEFI has been around for more than a decade.
You're trying to use a laptop like a versatile desktop. That doesn't always work. The BIOS/UEFI can be limited in the settings for one. In the case of dual boot I prefer a boot menu after POST that you can bring up with a hot key. Your device may or may not have that selection. The next option after that is making sure the GRUB file gets configured correctly and the easiest way for that to happen is install Win11 first.
Good luck with this. I don't mean to be rude but I have limited experience with laptops so if I didn't already say it I can't help with anything else.
One last point. Laptops are not fragile, but they do require that you have the right tools and when removing the bottom cover since there can be wires so you lift carefully. Electrostatic shock tends to happen in cooler/dryer conditions. If that's a problem THEN you need to ground yourself. I've NEVER damaged a component from electrostatic shock and I've never worn a wrist strap. When it's cold I like to have something next to me that's metal and plugged into a wall outlet, that I can touch before doing work. Pretty basic stuff. I've put together 30 - 40 systems. Common sense goes a long way. Avoid touching the copper contacts on boards, disks, etc....