This has been around for a little while I believe; there's going to be a ticketed 'development showing' in the Australian city of Wollongong on 3-4 May.
http://merrigong.com.au/shows/good-omens-development-showing/
In the unlikely event that any BWW posters happen to be in the vicinity of Wollongong around that time, and decide to go along, please let us know what this is like TBH the book wasn't my thing, but this is such a major property that I'm curious. Given the imminent TV miniseries, if this musical is ever likely to gain momentum I imagine it would be now or soon.
Some videos from a 2017 concert reading here:
https://www.goodomensthemusical.com/media