How can I restore Books that are no longer available but previously downloaded?

I have about three dozen books on my old iPad which are no longer in the bookstore. These books are all downloaded on my old iPad, and books are synced to iCloud.

How can I install these books on my newer iPad? It, too, is synced to iCloud, but these books missing from the bookstore don't show up on my new iPad.

Same question, but for the Mac:

All the books on my old iPad show up on my old Mac (Intel) but do not show up on my new Mac (M2 Max).

So, how can I get these books to also show up on my new Mac?

Bottom line: I want all the books on my old iPad and old Mac to also be on my new iPad and new Mac. How can I get these books which I have downloaded on my old devices copied to my new devices?

Thanks!

[Re-Titled by Moderator]