The only SUCCESSFUL AND RELIABLE way I found to prevent Windows 10 from doing this shit was to remove the HDD from my ThinkPad on which I have Linux, then install Windows on SSD, then put back Linux HDD, then in BIOS deprioritise booting SSD, so I can only manually select and boot SSD/Windows when I really want to use it.
This approach means there is only 1 existing OS on my machine – Linux (Debian) – unless I quick select different boot device. There is nothing that can defeat this approach, and is the best one.