Dual Booting W10/Ubuntu with 2 separate SSDs in UEFI mode

The options to choose where to install boot loader in UEFI mode do not work.

The old Ubuntu install entry in NVMe drive will be overwritten and boot new install.

Posted work around to manually unmount & mount correct ESP during install #23 & #26. Very old bug but still an issue if not installing to same drive as Windows.

https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1396379

Others suggest disconnecting all other drives physically or logically in UEFI settings, so install drive is first drive.

Or removing boot flag/esp flag from first drive, so only ESP is install drive. See Tim Richardson's answer in second link in concord42's answer above.

How do I install Ubuntu to a USB key? (without using Startup Disk Creator)

Or if you have ESP on second or external drive, you can just reinstall grub, either manually or using Boot-Repair's advanced mode & full reinstall to correct drive.

If you have ESP on second drive, use Boot-Repair's advanced mode to reinstall grub to second drive. Default fix may not be correct, only use advanced mode. Grub installs to any drive without issue, it is Ubuntu's Ubiquity installer that only wants to use first ESP found.

https://help.ubuntu.com/community/Boot-Repair

UEFI/gpt partitioning in Advance, newer versions do not need swap partition as swap file is now used as default since 17.10, but some still prefer swap partition and it will be used if created in advance:

How to prepare a disk on an EFI based PC for Ubuntu?

Windows settings also required, if you want to dual boot or read NTFS partitions from Ubuntu. Particularly UEFI fast boot and Windows fast start up.

https://help.ubuntu.com/community/UEFI