Subsite as a Repository

Dear WP Experts,

I need to work on a WP multisite. With:
– Main site https://www.domain.com
– Subsite1 https://www.domain.com/subsite1
– Subsite2 https://www.domain.com/subsite2
– …
– SubsiteN https://www.domain.com/subsiteN

Main Site, Subsite1, 2, etc. will be using exactly the same data.

To avoid posts duplication so for easier maintenance purpose, I just wonder if:
1/ I could use SubsiteN as a repository with:
– Custom Post Types as CI;
– and related Custom fields as CI’s attributes.
2/ Then I could query this repository from Main Site, Subsite1, 2, etc. to manipulate/populate Main Site, Subsite1, 2, etc. posts’ data with SubsiteN’s data.

As we are dealing with the same database, I thought I could have made it easily, but answers in Groups are not that straightforward or seem to be no.
– Is it really impossible? Should I modify my data strategy? And how?
– If it is not, could you please revert me to a tutorial I might have missed?
– Any feedbacks on this strategy will be also appreciated.

I do thank you for your time to my questions. I am quite new to WP dev.

BRgds, NLE92500