Yes, "matching same sensitivity between games" doesn't seem to have much real world merit when you look at professional players or renowned aimers. You can get used to new and different sensitivities much faster than you would think. If anything, it would make sense to train aiming and sensitivity like any other mechanical skill: starting slow and precise and eventually increasing speed so you can do the same motion just as precise at a higher, more useful speed. This is a bit at odds with how aiming works at high and low sens, low being primarily arm aiming and high being primarily wrist and finger aiming. If you train at both spectrums of sensitivity, theoretically you would be good at all aiming types, arm, wrist and finger.
0% MM is the only match that has any mathematical basis behind it, the rest are just arbitrarily picking a point on the screen to match for, whether you think this matters at all in-game is the debate. Is there a reason why most CSGO pros us 75% MM besides that is the game default? Why do some use more than default? If you're going to pick one, you might as well pick 0% as it's the only one that has an actual consistent ratio, and it's the default sens for games like Apex and Call of Duty. It also is extremely prevalent among overwatch pros. It is the only ratio that "matches" regardless of resolution and aspect ratio.
Aiming seems to have more to do with your relationship with the mouse and how to handle it than the actual consistent distance you move it. It's why someone like shroud just has good aim, it doesn't really matter what sens he uses he just knows how to aim. That being said slowing down any mechanical skill makes your more consistent and speeding it up makes you less consistent.