Garmin Explore has some cool feature

What's even cooler is if you have multiple devices connected at once like a watch and handheld, you can choose which device or all of them to nav the same course.  There certainly have been steady improvements to Explore over the past few years.

Can you explain a real life example of why someone would use this? "It allows to upload new course *during* activity. So if you're hiking and decide you need to quickly plan a route - you can easily create one in Garmin Explore"

Plenty - during vacation we decided to make a hike and mid hike I got tired of peeking into the phone (sweat, unblocking, hate it), so I uploaded a route. Also if your pre-planned course is wrong or you are unable to complete it - you can create a modified 're-routed' course during activity. Definitely not as good as having a full map in F7 with auto-rerouting, but welp, usefull for me :) 

Also note - you don't need to select stuff in the watch - the moment you hit 'navigate' in app you're good to go :) 

Awesome :) 

The Explore app can be used off network.  So if you plan ahead and have maps of your area downloaded, you can use the phone interface to view your surroundings.  You also are able to take your Explore collections of courses/waypoints with you.  Much easier to view that information on the phone than the watch.  You can still nav on the phone is you want, but if you're in a phone battery crunch, you can offload the nav work to the watch.

Explore + Instinct 2 is the only GPS/Navigation I needed for backcountry canoe/portage travelling. The idea of a full map on a watch is nice, but it's only useful if you haven't planned ahead or need to make unexpected changes and DON'T have a phone/Explore with you. If you've planned your routes and points of interest, Instinct 2 is all you need. Keep the phone off unless you need to change courses.

Yep, I mostly upload courses and get rolling. During bike rides or long (30km+) runs I sometimes need to reroute. The only thing that bothers me about I2 is the 50 point limit for course. 50km+ bike ride and your easily reach this and run into all sorts of issues :) 

Will it also work with Edge 530/830?

No

Is it inReach Explorer or Edge Explorer?