Paragliding pilots usually have a side mounted reserve chute in the harness. Sometimes, they have two (one on each side), mostly acro pilots.
Attaching an reserve chute to an essential and used part of a paramotor is imho not a good idea. If the carabiners fail during flight you have nothing left, except for falling down. Besides, when attaching and detaching every time, you add an extra moment of failure.