boot with proxmox installer usb and ctrl+F3 to go in a tty console

create new zfs dataset named rpool like the previous but using the new block device

import old zfs pool with a new name like rpoolold ( with zpool import take note of id of the old pool to be renamed )

zpool import idofoldpool rpoolold

create a snapshot for every source dataset to be migrated

zfs snapshot -r rpoolold@nameofsnap

copy datasets from rpoolold to new rpool

zfs send -R rpoolold@nameofsnap |zfs receive -v rpool -F

set the right mountpoint in the new copied root pve dataset to make proxmox bootable

zfs set mountpoint=/ rpool/ROOT/pve-1