For linear nonuniform cellular automata (NUCA) which are local perturbations of linear CA over a group universe G and a finite-dimensional vector space alphabet V over an arbitrary field k, we investigate their Dedekind finiteness property, also known as the direct finiteness property, i.e., left or right invertibility implies invertibility. We say that the group G is
$L^1$
-surjunctive, resp. finitely
$L^1$
-surjunctive, if all such linear NUCA are automatically surjective whenever they are stably injective, resp. when in addition k is finite. In parallel, we introduce the ring
$D^1(k[G])$
which is the Cartesian product
$k[G] \times (k[G])[G]$
as an additive group but the multiplication is twisted in the second component. The ring
$D^1(k[G])$
contains naturally the group ring
$k[G]$
and we obtain a dynamical characterization of its stable finiteness for every field k in terms of the finite
$L^1$
-surjunctivity of the group G, which holds, for example, when G is residually finite or initially subamenable. Our results extend known results in the case of CA.