I've spent a lot of hours playing Splatoon through Splatoon 3. Once I found that the Steam Controller a few years ago I was sold that I could play PC games with motion controls and prefer it to keyboard and mouse. I've played keyboard and mouse games over the years and still do on occasion. It is just hard to go back to have the better joystick movement than wasd and motion control aiming. By far my favorite way to play games now.
First how you sit and hold the controller matters. I've found that holding the controller and resting my elbows/forearms on my knees (or an office chair) so that my wrists can move freely is the best. If my wrists are not relaxed aiming is much much harder. In all cases I can my gyro is on by default, but on PC I dedicate a face button to turn off motion control while held to recenter. Better is a button like Splatoon has that recenters the view, but that requires games support.
Just practice aiming, and if it is too hard turn down sensitivity until it feels better. Continue practicing and once you feel comfortable you probably feel like you cannot turn fast enough with gyro aiming. At this point turn the sensitivity up. Practice and repeat until you feel you can turn fast enough or you can't keep a good aim and then turn it down slightly. After thousands of hours of motion control I do sometimes have to tweak sensitivity for certain games, especially when first playing with motion control on the game. Some games I have higher sensitivity, some I have lower, it really depends on the game. For PC games all camera control is through motion control on my steam controller with a dedicated turn off motion when held face button.
If you can try a Splatoon the motion tutorial is pretty good, and the single player campaign good practice (or Octo Expansion on Splatoon 2). I personally find that motion control while using the Switch as a mobile console is uncomfortable, the switch pro-controller is much better but separating the two joycons works well enough.