I've had a podcast called Games From Folktales for some time, and it tends to contain Ars Magica material. Transcripts are at https://gamesfromfolktales.com/ My first project for the Open License is Mythic Venice, The first chapter, in pdf and audio, is free here: Ashcan and audio of Mythic Venice Chapter One – Games From Folktales
The complete text has been released to my Patreons, who are over on https://www.patreon.com/TimothyFerguson The plan is for it to be "pay what you want" on Drivethru or somewhere similar. It's ready to go when the license goes live.
That will be followed by my podcast's bestiary. The last version of this, which came out in 2020, is up here for free. Episode 250 – Half-remembered monsters – Games From Folktales The goal is to add extra materials for people to use in their own work. I'm also writing an index of creatures with Might in all of the Fifth edition supplements, to make supplement development easier. It's likely to be finished this weekend. I'm going alphabetically I'd I've just reached the Realms of Power books, which will prove a challenge.
After that, it looks like a Sicily book, but I'm still scoping the source material. The alternative is a Cheshire and Flintshire book.