I trained a handful of folks for free before the seminar, waiver, cert, and insurance free. I made it very clear to them that I was "helping" them what I knew, not "coaching" them (dunno why that was significant to me, but it seemed to make it feel better) and that I was trying to learn to coach better. They were also my friends, so I didn't have to solicit strangers into some kind of arrangement. I made it known that I wanted practice helping people learn the lifts and people came to me. I also had them use the app and read the book. I was present while they did what the app told them to do, and I helped them follow what the book and app said. We paid to have a membership in the same gym, where we all signed the waiver for the gym.
Not sure that ANY of this would have protected me if someone had become injured while trying to perform the lifts the way that I was telling them to, but my FEELS (and the feels of my trainees) were assuaged because there was something else of authority we were following. I literally didn't let them call me coach until I passed, although sometimes they tried to anyway. I was a friend helping out my friends. If you're concerned about legal issues, you may try it this way.
Also, I believe that if you attend a seminar, your Certificate of Attendance qualifies you for insurance through Sports & Fitness Insurance. It says so here:
seminar-course | The Aasgaard Company. You could attend a seminar, learn a lot about the method, and then cover your ass for pre-cert coaching by getting insured.