While there's a lot of argument about what No Man's Sky does or doesn't feature, what no one has found yet is if it has a planet entirely populated by Marios. Until that's found, if you're wanting a Mario/No Man's Sky mash-up it may be better to just take a shortcut and install No Mario's Sky, a procedurally generated Mario exploration game.
Created for Ludum Dare, No Mario's Sky lets you fly your plumber through a universe of ever-developing levels. Whenever you get bored of the planet you can tap 'X' and summon your spaceship, launch yourself through the atmosphere and fly off into a galaxy filled with other worlds.
Each planet has a weird variation of the traditional Goomba, emulating No Man's Sky's incredibly varied wildlife. Even the music gets a procedural twist, with every planet having a different take on the Mario theme, sometimes going so far as to change the instrument it's played on.
It's not a deep game but it is bloody large, with billions of planets to visit, and it's free, too, so it's well worth a try.
And, if you've time, it's still worth trying out Norman's Sky, the 8-bit version of the infinite space explorer.