Sadly, I also can buy games only via Steam for now due to payment restrictions, and I'm looking forward for a Steam release (following you for many years, love the first game, played it on itch.io and on Steam afterwards). And it's more convenient - I have some games on itch.io, that afterwards came to Steam (at that time it was possible to pay through itch.io) - if I had a choice at the moment, I would've bought it there.
So I'm going against my one wishes, but...But those are very valid concerns - and why do yourself a disservice (a lot of work for potentionall risks)? I dunno if there's a bigger market on Steam than on itch.io for VNs, maybe? Many of my gamer friends use exclusive steam/gog/epic/ea and dont even know about itch.io)) but everybody playing VNs knows this platform. So maybe do max sales here and then go on Steam?
But anyways I'm glad the game is out, it's a great milestone! Any choice you make - looking forward to play, either on Steam, or is I'll be able someday to purchase here!