Best phone app to create/import tracks to use with Fenix 6

I’m searching for an app that can use a .img map file (openstreet)

Then I want to create a track from scratch and save as .gpx , and be able to import and edit a .gpx file (example: from Wikiloc)

Other functions

- use .img map as a layer (offline)

- use Google Maps Satellite pictures as a layer (mobile network)

- navigate using the gpx file

Why? 

- Stop using Basecamp, is too much and outdated

- import courses from Wikiloc and edit it

- create courses that don't exist in Wikiloc

- send to Fenix 6X

- use my mobile phone as a backup device and send gpx files to my friends that don't have a watch and rely on the mobile phone to navigate. That way they can discuss, edit and navigate that track.

Any recommendations of an Android app able to do that?

Ps: Garmin Explore is not functioning properly with current firmware.

Basecamp? Several hours to read maps of the watch.