Playing with a keyboard and mouse is easier, because the missions require head shots to kill people. There's times if I shoot a person in the body, they go down, but get back up. I tried playing the very 1st online mission and couldn't do it with a controller. Then I watched a video and realized I only had to kill a few people near the entrance, get the drugs, and run. I did it with a keyboard and mouse and it was easy.
http://www.youtube.com/watch?v=4t0i-8wg6Wk
Then I played the next Trevor level where he kills 25 rednecks. I had to do it a couple times because I was using a semi automatic rifle. In this video the guy is using an AK and easily does it.
http://www.youtube.com/watch?v=gx_JDeqbQVc
So we can make a stereotype that most games revolve around getting head shots. That's why there's trainers like Aimlab. I need one for the Steam Deck using a controller, because it's hard.