There is no reason this couldn't be your main GPS unit. It is good enough for that no problem.
Sure the screen isn't as big as most smart phones.
In todays tech abilities the smart phone with Onx is the way to go, for me personally.
But the Garmin InReach is no doubt a good enough system to be a stand alone GPS unit.
Just wanted to point that out.
Why if your using the InReach and your smart phone are you paying for the ONX maps when for less money you could be using the Garmin Earth mate hunt addition?