UEFI won’t boot from MBR drives unless it’s in BIOS compatibility mode. What format the drive is in isn’t determined by a firmware setting, though it can affect the boot process. I don’t think you actually understand what you are talking about here. The easiest way to install OSes both Windows and Linux is by wiping the drive, which would have solved this issue. Dual boot on single drive configurations normally have issues and will always be more complicated. It’s better to use two drives where possible in most cases. I suggest you read up on BIOS vs UEFI and how partition tables work if you want to do a complex setup like that.
Mint is known for having older kernels and therefore not supporting the latest hardware. They have a different edition for newer computers called Linux Mint Edge edition. Something Arch derived like CachyOS or another distro using recent kernels will always have the best support for bleeding edge hardware. The CachyOS installer is also pretty friendly, though maybe not as much as Mint.
You understand that technical people often are the least likely to trust new technology and are often stuck in the mud when it comes to technology? Doubly so if you are anti-corporation. It seems anything that isn’t the Unix way of doing things can be questioned.
There is a good meme about people who love technology vs people who actually work with the stuff. The former using IoT devices to turn their lights on while the latter uses a light switch and has a gun in case the printer starts making weird noises.