Hi, thank you for your interest! We had an application form for the initial onboarding from which we whitelisted the most suitable organizations. An upgrade to Lido for Terra (bLUNA) is in the works. Around the time when this goes live (within the next 1-3 months), it is likely we will have a second onboarding wave where new operators can apply.
In general, the Lido node operator governance is still evolving, we have written up a bunch of our decision making criteria here: Node Operator Sub Governance & New Node Operator Application Process - #4 by FelixLts
In the near future, we will formalize it some more and document that.