GPSMAP 66i and Fenix 7 pro solar

I don't have a watch, but I have a 66i. Since the watch records the activity and provides you with heart rate, my suggestion would be to use the 66i for communications, not navigation.  Place the GPS in Demo, and this should extend your battery life.

I am not sure what the question is.

Activity recording on the two devices is independent. You can record on either one (alone) or on both. If you do record on both, the two are independent.

I believe you can use the F7 pro solar to remote control the 66i. I don't an F7, but I do have an F5X+, which can serve as a remote control. To get started on this on the watch, go to Settings > Sensors & Accessories > Add New > inReach.  This will search for an iR device via ANT+, which must be enabled on the 66i.

Once everything is linked, you may have to add the inReach control. Been so long that I cannot remember if I had to do this or not. Once the control is added, you will see it in the controls menu (long press LIGHT). Opening the iR control will give you remote control functions, as well as minimal status and notification information.

Thank you very much for the answers.
My question is about how to best use two devices that do similar tasks. In other words, I wanted to know, because I can't find this information anywhere, if Garmin thought about an integration at the activity level as it did with inreach.

I will give an example, the F7 has cardio, the F7 shares the cardio with the 66i, the 66i has a better antenna, and can record the activity. Combine the data in the sense of optimizing the battery, and the data. this is my question.

but, thanks for the answers, i already have an idea of what i can integrate. thanks, pv

I have both, like you, While trekking I only use the 66i. To follow my tcx tracks that I upload to it, and also to record my track while walking.

I do not us the 7x at all, (unless I have no battery for the 66i) because I dont need to keep an eye on the cardio, walking doesn't really work the heart so I don't bother watching it, that way I have plenty of battery for the 7x, I did notice that using the inReach Remote on the 7x widget drains the battery, so I no longer use that. For info I find I can squeeze three days from the 66i with following and recording my trek, about 7 to 10 hours per day

You could also add a heart rate monitor to the 66i if really needed, chest or arm band.

Looking at the basics alone the 66i is simply a better option for navigation.

I treat the watch as an emergency backup, it's always attached & ready if everything else went pear shaped and you lost the rest of your gear. 

I use both.  I use my Fenix HR 3 to broadcast the heart rate to my 66i.  The 66i would then embed the heart rate as a new field in the GPX file of the 66i.

So your 66i is using the Fenix as an external ANT HR Sensor.

If this really works, this must be represented in the .gpx as a Garmin extension. The data should be safely ignored by non-Garmin applications which read .gpx.

It does.  I can then can display it in my 66i  as a data field.  Calories and max/min heart rate are also displayed in the Garmin Connect page for the activity.