I am looking for a way to send a private message through the Google Chat API

associated github issue : https://github.com/googleapis/google-api-nodejs-client/issues/3553

First, I had to sign up for Google Workspace (I’m still not sure why, as it is sometimes mentioned that Google Chat is accessible to everyone). Once that was done, I was able to create spaces, BUT:

I cannot create a space with multiple users directly (the space is created with one user, and then the others receive invitations via email). I looked into how to automatically accept invitations, but it doesn’t seem to work if everyone is not part of the same workspace. (chat.spaces.create and then for each member chat.spaces.members.create )

I am unable to send private messages (1:1 conversations) without an existing common space. (chat.spaces.messages.create with privateMessageViewer).