Every studio asks you to wishlist. As the publisher of Age of Medieval, here is the honest reason.
For an unreleased game, wishlists are the main number Steam has to judge interest. A game with more of them gets shown to more people who play similar games, before and at launch. For a first game from a small studio, that visibility cannot be bought any other way.
What you get: an email and a notification from Steam on release day, 17 May 2027, and another if there is ever a discount. Nothing is charged and you can remove it at any time.
Following the game is a separate click, and it is the one that puts posts like this in your feed. If the game looks like yours, do both.
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/