That adds about $200. You can get a torque wrench much cheaper but not one that goes up to the spec the Garmin pedals require.

Also means if you're traveling and want to just bring your pedals instead of the whole bike, and rent a bike where you're going, you need to bring your wrench or have somebody install them for you.

I bought a pedal-based PM for the reason you mentioned, portability between bikes. In practice that's more limited than you'd think, and the P1 pedals are an improvement.

Both pedal-based meters require a specific cleat. You can move them back and forth between a road racing bike and a gravel bike (or even a MTB), but Keo cleats don't work very well on dirt roads if you ever put your foot down for any reason.

That's been my experience with them.