When will registration for Private Access Token issuers become available?

I am interested in experimenting with Private Access Tokens with some of our orgs web security services. I am unable to use any of the token issuers available today. The documentation states that registration will be available for other issues. Is there an estimated date when that will become available? I dont see any such registration at https://register.apple.com

We are planning on opening up registration at the link you have provided late this year, so please keep checking back for updates on this later in the year.

When will registration for Private Access Token issuers become available?
 
 
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