How can I restore Smart Mailboxes from one Mac to another?

Machines are (a) M2 MacBook Air [24GB, 2TB] and (b) 2018 i7 Intel Mini [64GB, 2TB]. I updated both from Sonoma to Sequoia, installed all updates. Both systems are on Sequoia.

On the M2 MacBook Air, all my smart mailboxes disappeared. The emails remained in the inboxes, but of course, my long-useful smart mailbox organization was gone. On the Intel Mini, the smart mailboxes are still intact.

(1) Is there a file(s) on my Mini that I can copy to my M2 and restore the smart mailboxes? (2) How can I keep this from happening with future OS updates? Any help greatly appreciated, thanks.