FWIW, here's my little pax brief "spiel":
Prop - Doesn't look like much but can transfer xxx HP to the air. It'll win every time from your limbs. Don't go near it. If you see an aircraft without a prop, it's probably not broken but spinning.
Doors, windows - Explain how to open/close them, including any special emergency switches.
Seatbelts - Some might be unfamiliar design. Leave them on at all times. There's no loo on board, so where would you go anyway?
Headset/Intercom - I help them put it on and adjust it. Mic needs to be "kissing distance" from your lips. We can talk to each other but ATC is on it as well. Sterile cockpit during take-off and landing, and other busy times. Also explain what a callsign (and the abbreviated version) is, because they'll be hearing that a lot. Also volume knob on their headset.
Controls - I show the range of travel of the yoke/stick so they know what it can do. Also, don't touch anything or interfere with anything unless I told you so. If you accidently did something (throw a switch, say), tell me about it rather than letting me find out.
VFR rules - we fly on visual separation without much help from ATC. If you spot another aircraft, tell me about it. And you may interrupt me at all times for that.
Sickbags - depending on the nervousness of the pax I either tell them about it or make sure I know where to find them in a hurry.
Furthermore during the taxi, runup and flight I tell them anything that might be unusual. In the DA40 for instance I explain that taxi is a bit wobbly due to the castoring nosewheel and differential braking (effectively hiding my inability to taxi straight despite this
). Before the runup checks I tell them I'm going to test the engine and its controls to check that everything works as designed. Approaching the circuit I sort of explain them the route we're going to travel to get to the runway.
Most of this is done while walking to, and getting settled in the aircraft. Apart from the VFR rules and "tell me if you don't feel well" there is no specific safety brief.