I want to make a journey by foot through europe of about 800km long. Can the Garmin Inreach Explorer+ or mini hold the route for this?

I'm considering to buy a Garmin Inreach product.

I want to make a journey by foot through europe of about 800km long.
Can I prepare this route in the MapShare environment and then Can the Garmin Inreach Explorer+ or mini hold the route for this?
I won't be able to access a windows computer during the journey. I do have a Smartphone with me.

Does anyone know or have experience with this?