Here's the link to a blog post about ISC2 exam development. To be involved you need to hold the appropriate certification(s).
https://blog.isc2.org/isc2_blog/2020/10/share-your-expertise-help-develop-isc%C2%B2-exams.html
Currently they are looking for:
- CISSP-ISSAP
- CISSP-ISSEP
- CISSP-ISSMP
- CAP
- CSSLP
- HCISPP
- SSCP
But you can still register to help with other certifications such as CISSP when the time comes.