This is just my personal opinion and this is not a place for yet another Systemd-war... but...

Systemd could work just fine in the future but it could be also a huge risk in a somewhat exotic software/hardware project as it seems to be hogging everything into one huge monolith ball of everything-that-is-not-unix one dependency at a time. To me, that is not a matter of preference but practicality.

On the other hand, Devuan seems to be maturing into a self sustaining fork quite slowly.

If a piece of hardware handles Devuan without a hiccup, it should be somewhat straightforward to customize and install Debian on it pretty painlessly as well (?). I suppose it might be a more difficult process the other way around as Devuan is (at least philosophically) closer to what Maemo was originally built on.

I am happy for the options existing either way.