I recently had a Debian 12 (bookworm) fail somewhere in the boot process. The EFI firmware didn't recognize the nvme device. However, the d-i netinst not only recognized the device, but recognized the encrypted partition on it, and the LVM PV in the encrypted partition. After I gave it the password for the encrypted partition, it made the LVs available to me, and I was able to chroot into the system.
So it looks like everything you need to open an encrypted partition and PV within that already exists on the d-i installer. Alas, they are not available in partman when installing. Instead I installed Debian 13 (trixie), and spent most of two days restoring programs and data. This line from syslog might be a hint: Sep 10 16:08:05 main-menu[464]: (process:6666): /lib/partman/active_partition/86opal_factory_reset/choices: line 8: /sbin/cryptsetup: not found -- Does anybody read signatures any more? https://charlescurley.com https://charlescurley.com/blog/
