Getting Keyless people in the community.
Perhaps a way to entice people without keys onto the community, Is to allow people to access to a small pre built map to see how well it works. Letting them move parts of the map around as they like.
Problem is they still need the game to do that.
Well that does cause an issue.
Do you know if Talespire is compatible with steam's remote play together? That may help although there still needs to be one person with the game.
Alternatively another option I was discussing with some friends is the potential for streaming via discord - you may have to get the streamer to do dice rolls or move items for you but they can see how it works potentially.