If you don’t want it made public I believe you can post it in the Professional Appraisal section and it won’t be indexed (apparently).
Having said that, very few of the .global sales on Namebio appear to be aftermarket related. Most seem to be sales from the operator or affiliates.
Difficult to put a value on it without much history to work from.
You’re also welcome to post it to my website (PeerIdeas) to get a range of subjective valuations for comparison. We’ve only seen one other .global listed recently so more would be helpful.