Change /etc/apt/sources.list to contain the following (remove 'contrib' and 'non-free' if you don't use those.)

deb http://archive.devuan.org/merged jessie main contrib non-free
deb http://archive.devuan.org/merged jessie-security main contrib non-free

Then run

apt-get update
apt-get --allow-unauthenticated install devuan-keyring

If that doesn't work, you might need to download the deb package and install it with dpkg.

wget https://pkgmaster.devuan.org/devuan/pool/main/d/devuan-keyring/devuan-keyring_2022.11.15_all.deb
dpkg -i devuan_keyring_2022.11.15_all.deb

apt-get update
apt-get upgrade
apt-get dist-upgrade

If you don't have the kernel metapackage installed, you'll need to install whatever is the latest kernel for jessie. That will happen automatically if linux-image-amd64 or linux-image-686-pae is installed.

If you have some desktop other than xfce, it might be more difficult.

So: It is a wheezy install. But since is has 2 RAID 1 crypted volumes, I'd like to avoid a new install..

I thought to try to update from wheezy to debian jessy and than to devuan beowulf and up to chimeara.

Bad idea?  Any hints appreciated.

EDIT: Well, I answer myself. For some additional reasons it is. Searching a suitable mainboard for a NAS setup now.
Hard to find with my wishlist.
4 x SATA
-1x m2 sata
NO Intel board
integrated cpu prefered

Was aiming for pine Quartz4 plus Sata card over the PCIe slot. But can'T find a place to get that board..