It seems like you may be modifying the USB live installer's grub files. That has a somewhat different grub that is configured with just the files it needs to boot, not all grub files to boot any configuration you may install. Do not modify installer, or you may have modified it enough already that you need to create a new one. You should always have a current version live installer to be able to boot to make repairs or certain changes if needed.
You have boot flag on sda1 as it says it is the ESP - efi system partition.
UEFI is the very first thing that loads and has replaced BIOS. It also normally has a fast boot setting where it does not check for changes (which is often the case) and just immediately turns over to boot system. A standard startup goes thru various checks for what hardware you have and stores that where operating system can find it, so operating system knows what hardware you have. Often best to turn off fast boot in UEFI or some have time settings (my motherboard let me set it to 3 sec) so you can press correct key (often del or f2) to get into UEFI to change settings or choose which system to boot.
You should also have a one time boot key like f10 or f12 that should show boot options. It may show both CSM/BIOS & UEFI but since your install is UEFI you must only use UEFI settings.
These are your UEFI boot entries. Not sure why you have duplicate network boot entries, which rarely are used. And Ubuntu entry is not standard, but I do not fully understand all the versions of entries that efibootmgr shows.
Code:
efibootmgr -v
BootCurrent: 0003
Timeout: 0 seconds
BootOrder: 0000,0001,0002,0003,0009,000A,000B
Boot0000* ubuntu Vendor(99e275e7-75a0-4b37-a2e6-c5385e6c00cb,)
Boot0001* UEFI: IP4 Realtek PCIe FE Family Controller ACPI(a0341d0,0)PCI(1c,2)PCI(0,0)MAC(f8a963be35db,0)IPv4(0.0.0.0:0<->0.0.0.0:0,0, 0..BO
Boot0002* UEFI: IP6 Realtek PCIe FE Family Controller ACPI(a0341d0,0)PCI(1c,2)PCI(0,0)MAC(f8a963be35db,0)030d3c000000000000000000000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000..BO
Boot0003* UEFI: PNY USB 2.0 FD 1100 ACPI(a0341d0,0)PCI(1d,0)USB(1,0)USB(1,0)HD(1,800,1df2f00,0434dcc3)..BO
Boot0009* UEFI: IP4 Realtek PCIe FE Family Controller ACPI(a0341d0,0)PCI(1c,2)PCI(0,0)MAC(f8a963be35db,0)IPv4(0.0.0.0:0<->0.0.0.0:0,0, 0..BO
Boot000A* UEFI: IP6 Realtek PCIe FE Family Controller ACPI(a0341d0,0)PCI(1c,2)PCI(0,0)MAC(f8a963be35db,0)030d3c000000000000000000000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000..BO
Boot000B* UEFI: PNY USB 2.0 FD 1100 ACPI(a0341d0,0)PCI(1d,0)USB(1,0)USB(1,0)HD(1,800,1df2f00,837ec5d8)..BO
That is not showing any CSM/BIOS entries nor a hard drive boot entry.
This is my ubuntu entry & my hard drive boot entry, but a different UEFI, so your may never be identical. I manually added the bootx64.efi entry, just to see how it works, but do not have to use it as my UEFI will directly boot the ubuntu entry. I also do not need shim as I have secure boot off. With secure boot off, you can use shimx64.efi or grubx64.efi where shim only works (and signed kernels) if secure boot is on.
Code:
Boot0000* ubuntu HD(1,800,fa000,3195d314-ce88-42ac-beac-d9f80289ac11)File(\EFI\UBUNTU\SHIMX64.EFI)
Boot0009* UEFI OS HD(1,800,fa000,3195d314-ce88-42ac-beac-d9f80289ac11)File(\EFI\BOOT\BOOTX64.EFI)..BO
You may have to scroll right to see the exact files it is using to boot. And in both cases it boots with a grub.cfg in /EFI/ubuntu folder All the number info is related to the hard drive number and GUID for the ESP.
Some example UEFI screens, your may be similar but not identical.
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