Yeah, such a feature could be done by just having a button in the "New Game" screen. Of course, implementing this would take a lot of work and certainly wouldn't be ready by 1.0. That is, if it was an interactive tutorial and not just a few text screens explaining things. The former would be ideal, though.
But yeah, I could help plan out the actual tutorial when/if it comes time for it. I think the best way would be to have a simple prefab base (1 Skyranger hangar, 1 Interceptar hangar, the access lift, 1 barracks and 1 stores, and no soldiers/gear pre-owned.
Then, popup messages & greyed out menu options would direct the player to buy soldiers and weapons, then go back to the Geoscape to wait out time until they arrive. Then go through equipping them.
Then teach players about building facilities by having them build a lab and manufacturing plant, ordering scientists/engineers, and researching/building something simple like a Medkit.
After that, go back to the Geoscape and have a drone appear for teaching the player about Intercepting and shooting it down. After it's destroyed, have an "enemy base" appear that's just a prefab battlescape training course, and explain how to send soldiers there.
Then once landed, direct the player how to move/select units (by having one move to a specific tile) and then teach facing directions, opening doors, throwing grenades, shooting, things like that.
To keep it lore-friendly, it can all be set up as a training exercise, where no aliens are encountered yet. Targets are just wood targets or something similar. That way after completing the tutorial, your first real battles are still scary and stressful and you still get to have to figure a lot of things out on your own.