Could someone explain Running Power?

The RD Pod gets used in precedence.

I think the "excitement" is partly as cycling power meters are quite expensive but more and more are being used. Plus we all like to get something new for nothing right!

Simplistically power can be thought of as a single measure of how much effort you are putting in. In theory if you go uphill you obviously slow down but your power might be the same as when you go faster on the flat.

Why do you wear RD Pod and HRM Run? That makes no sense.

You have to do a test to get an estimation for your rFTPw (running Functional Treshold Power watt).
A test that does not Interrupt your normal Training to much https://runwithpower.net/tag/rftpw/
Another (better) Test is running 30min with Pace that you are able to run for one hour. Watt average of last 20min is your rFTPw.

To set the power zones there are many different suggestions. Matt Fitzgerald has very very low 1st zone so i cant believe that he has tested it by himself. Jim Vance suggests 7 Zones and does not fit to garmin

Ohh I like that! I have a hard time judging effort with hills

That's where Rate of Perceived Exertion (RPE) comes in - https://www.cdc.gov/physicalactivity/basics/measuring/exertion.htm

When all else fails that's what you need to have available all the time. Train by numbers, race by feel.

Thanks guys, I will check out those links when I get back from my group run this morning. I didn't know there was a test so that is very helpful.
schnellejugend I am wearing both the RD pod and HRM-Run right now only because I wanted to see where my heart rate was with the strap as opposed to the wrist because I think my wrist heart rate is pretty low for a hard run. Yesterday's run kind of proved that but I want to get a few runs in to compare. It's just habit to clip on the RD pod so there it is.

I have one (possibly dumb) question about the ftp test. How do I look at my run activity in GC and determine the watt average for only a portion (last 20 minutes) of the run?

I think this is not possible with Garmin Connect. I use Golden Cheetah for this. I have created a training for my 30min test: 15min warmup, 30min (divided in 3x 10min) test, 15min cooldown. Golden Cheetah shows single and combined intervalls with the metrics you want. Connect only shows averages of own not IQ metrics.
You should do this test only after a minimun of one better two rest days and repeat it every ~6 weeks.