Hello,
this thread got my attention because also I do not like descending quality of operating systems coming from Microsoft which force users to change their operating systems for apparently newer, better which actually cause more problems like privacy issues, incompatibility etc. I am using personal computers since Windows 98 and Windows XP. Windows XP was the last good operating system from Microsoft. August 2018 I decided to migrate to Linux and since then I have dual boot on my both old Dell laptop and PC, one with Windows XP Professional 32-bt and currently Linux Ubuntu server and one with Windows 7 Professional and Linux Mint. I also used Linux Ubuntu desktop in the past.
My BIOS is still Legacy BIOS, but current Linux distribution support also UEFI.
I'm not sure I understand concerns about dual boot - please correct me if I misunderstood, you think for dual boot with Linux a second disk is required. I admit, I did not read all post because I simply do not have that much time for that. But second disk is not required. But yes, Microsoft operating systems do not respect any other systems on disk so they simply do not care whether there is something other installed on disk than a Microsoft OS. That is, Linux MUST be installed on a disk drive with existing Windows partition.
I know, it requires courage, patience, careful acting, humility and willingness to learn Linux, because any mistake can cause trouble. However, that trouble force you to learn and make experience with these operating systems. And when one reaches such a skill level you can solve issues self is rewarded than with satisfaction. And that's a great feeling to maintain an operating systems, for most people it a secret. Operating systems which are considered to be very safe systems.
For those who use Linux operating systems I have an advice, instead of choosing being comfortable, just do as much as you can do in console using commands instead of desktop environment which so or so as limited possibilities and do not give up to early. Having dual boot and Linux as your secondary OS at the beginning of the adventure will reduce loss in case anything goes wrong. Although there are forums one can search for a solution or create a new thread.
But what with compatibility?
There are options to emulate Windows applications on Linux which I admit still do not work as we expect. There is more and more software created by vendors directly for Linux platforms, but sometimes backwards compatibility is the issue - due kernel/header difference. As for drivers for hardware Linux community is handling them very well, but I would lie if I told you there are no issues. But using Linus I feel more free.
I am using Linux only for internet, documents, music and movies, but there are graphics or video programs available for Linux and many more. However, their availability depends on the distribution ans sometimes you have to dig more to add an archived repository to be able to install a software which is not available for the specific distro, use older libraries etc.
I only use Windows for older games and music production software. Although nowadays more and more games are available for Linux.
That's probably not all I could share here, but it's what comes in my mind right now. Good luck for those who dare and go for Linux.