The store page of Age of Medieval lists one platform: Windows. We are asked about others, so here is the reasoning.
Our rule is that nothing leaves the studio untested, and "tested" for us means the whole battery: more than two hundred probes that open the game, play pieces of it and count failures. That battery runs on Windows, on the same kind of machine most of our players use.
Shipping for a system means running all of that there too, on real hardware, for every build and every fix. For a team our size, a second platform done properly is a second job. Done badly, it is a version of the game we cannot vouch for.
So at release we promise one platform and stand behind it. The system requirements on the store page are the ones we test against.
Age of Medieval is developed by UnderStudio in UnderStudio 2D and published by Brasa Interactive. It releases on 17 May 2027.
Age of Medieval on Steam: https://store.steampowered.com/app/3259670/
Official site: https://ageofmedieval.com/