It´s a very interesting question, specially what concerns about progress and leveling. It would be great that your accont is linked to every platform you play in (Epic, Steam, Xbox). I don´t mind if you have to buy another copy, but saving progress and linking it to your Chivalry account is something vital and essential to me.
The devs have not been able to fully confirm this yet, but they have said they are going to try implement it (not at launch, but afterwards). A Steam version won’t be available until later so they have another 12 months post-launch to get it ready (if possible).