Hi ZdeKor,
Thanks for your feedback. I'm sorry I didn't make this a bit more obvious. Testing the feature for so long made me ignore some of the basics. Due to the rollout, we currently have "no" service that supports B2B direct connect 🙂 The first service will be Shared Channels. So we all have to wait until Shared Channels are avaialble. Only in a Shared Channel you can invite guest via B2B direct connect. Even more important in any service that uses B2B direct connect the traditional model of B2B collab (guests user in your tenant) is currently not supported. In my lab tenant I can see Shared Channel controls in Teams Admin Center, but my users can not create shared channels. So it will take a few more days and hopefuly we will be ablte to test everything.
Ciao Marco