Maybe you can do what Tynan Sylvester did for Rimworld. Once released on steam, Tynan was given a number of keys he could distribite himself to the people who purchased the game way before it hit steam, like me. We could get the keys a few days later, but they were available and Rimworld is still overwhelmingly positive on steam, because nobody could say nothing to him.
I had easily over 300 hours in Rimworld before it hit Steam. I could see dumping plenty in Aven as well, but if you guys manage to get a system to supply steam keys going, that would be amazing, as I would love to hit you up with a positive review. I quite like what this game represents.