In the meanwhile I refactored it to run in a plain cheap vps (currently running on a 5€ ovh VPS) with a free supabase instance to go with it, to allow me to host it online for cheap so that at least it could be tried instead of just images and text about it. It has been previously deployed on an autoscaling cluster in AWS with all the bells and whistles and the open-source objective includes all the terraform files to automate that production use case, but otherwise can run perfectly fine for hundreds of players on a small VPS (the supabase free instance might not hold together though in that case).
Feel free to give it a spin. If you want to play against someone you don't need an account, just click "TRY IT!" and then choose "Invite someone for a Duel", send the link to the other person and try a duel with a pre-assembled deck. You can also try it by yourself by opening another tab (a private one is better so you don't experience it all collapsing into a single user if the tab idles or you refresh, since the last cookie will set both tabs to the same player).
You can also sign-up but only with Google OAuth2 - the original was using Sendgrid which no longer offers free email delivery and I haven't researched an alternative yet nor set raw email delivery.
If you like what you see consider backing the campaign, there's a link on the landing page too. While mostly it'a ready for mobile browsing, some of the things done just for the BETA (such as the try it views when waiting for a player) might not show 100% correctly - everything else should be fine.
Let me know what you think.