Dual-boot Linux and Windows from different drives?

Question

linux

Hey!
The background is this:
I decided to first look at Linux, maybe even settle there.
Linux raised a 250 GB volume from the existing HDD, manually marking root, swap, home there, specifying the current windows bootloader, which is located on the SSD, as the bootloader. Thus, GRUB was born at startup and I could fully see Linux, and then reboot into windows.
It's great, it was decided to allocate 1TB of Linux from stores.
Now:
Linux is pre-cut from the HDD and the place is glued back to Windows. GRUB has not gone anywhere, if you go to the Boot Menu, then 2 options are visible 1. Windows Boot loader, 2. Ubuntu, among the rest.
If you choose ubuntu, I will get the grub console with a preliminary read_error(). there is nowhere to load the user rudely.
In the BIOS, Windows loads immediately, so there are no problems.
Bought a 1TB WD HDD.
How to put Mint on it and it loads either in windows or in linux?
On the one hand, you probably don’t need to mark anything with your hands, just select an empty hdd and linux will fully install there, and in theory the bootloader will also be registered there. BUT GRUB is already there, next to the prominent one, but it doesn't load anywhere.
Will a full-fledged installation on another HDD wipe out my Windows, as if there were no other OS at all?
It's just that, logically, in the boot order, I will be the first to load the hard drive from Linux, it will start rudely and give me boot options with Windows. Seemed to be a profit. But nowhere is there a word about this, everyone says almost a UFI partition, create and put a bootloader there, mark up an empty hard and put a bootloader with an EFI partition (which, alas, installing linux mint does not allow you to do this, even if such a partition is marked on a new hard) .
How to cut out an existing GRUB for the purpose of further reinstallation, even if it is the same as it was?
fix MBR by writing:
bootsect /nt60 C: /mbr
from Windows - do not offer, does not work.
And finally, the most important - backups.
How to save the current state of bootloaders with the ability to return everything later?
Boot-repair Linux here is what issued: https://pastebin.com/8xNRrpm2
(More info, doesn't fit here)
Explanations:
/sda - new 1TB screw - Linux is needed here
/sdc - current 2TB screw -file dumper
/nvme0n1* - SSD where Windows is installed.
/sdb - bootable flash drive with Linux.

Answer 1

The solution in my case is this:
In the Linux installer, at the stage of choosing the option to work with the disk, select "other".
Find your separate hard drive under Linux, create a new partition table on it.
Divide the free space into 4 parts:
The bootloader installation location is the EFI sector that was created above on the same hard.
As a result, the system got up on this hard, the bootloader on the SDD was updated and allows you to boot into both systems.

Answer 2

Windows does not see the screw partitions in the ext2-ext4 system
if it is difficult to work in the console = put the GParted window editor
in my opinion it is in the turnips of any of the debian-like
boot from a flash drive and treat it
properly under Linux terrobyte ???
collapsed from oak :)
20-50 is enough for the eyes for the system
20-50 for the home directory HOME
the rest is in the trash
if the ssd disk and little memory = swapping is not needed (on a home machine)