What can be done, following Kato and Fukaya-Kato, is to define a mod $p$ object $\mathcal L(\rho)$ which - if the conjecture on special values are true - encodes whether or not the special values divided by the period specified in the Bloch-Kato conjectures is a $p$-adic unit or not. More precisely, that element $\mathcal L(\rho)$ belongs to $\mathbb F_p$ and is well-defined modula an element of $\mathbb F^\times_p$ (thensic!). The $\mathcal L(\rho)$ is a rather weak version of a mod $p$ $p$-adic $L$-function but probably the best you can do in that level of generality in view of the multiple ambiguities in the definition of special values to begin with).
Independently of the truth of the conjecture on special values, itone may wonder if $\mathcal L(\rho_1)$ is then true that congruent geometric* Galois representations will have the sameequal to $\mathcal L(\rho)$$\mathcal L(\rho_2)$ whenever (so$\rho_1\equiv\rho_2$ modulo $p$. If that is the case, we may denote itthis common element $\mathcal L(\bar{\rho})$ (remember though that $\mathcal L(\bar{\rho})$ is just an element of $\mathbb F_p$ modulo $\mathbb F^\times_p$). In general, one cannot even do this, as the pair provided$E_3,E_4$ above establishes.
However, if either 1) we strip $L$-functions of their Euler factors at all primes of bad reduction (that case is mostly formal) or 2) the two Galois representations are geometric* and belong to the same irreducible components of the universal deformation space of their common $\bar{\rho}$ (that case requires some work). The pair, then $E_3,E_4$ above establish that such a statement$\mathcal L(\bar{\rho})$ is definitely not true without 1) or 2) and a slightly more involvedwell-defined. One can find counter-example showsexamples showing that the requirement that both representations be geometric is also necessary (that is to say, there exist congruent Galois representations belonging to the same irreducible component of the universal deformation space of their common $\bar{\rho}$ but with non-isomorphicdifferent $\mathcal L(\rho)$).
In conclusion, yes, congruences between special values coming from congruences between the underlying objects (Kummer congruences, if you want) abound and there is an object $\mathcal L(\bar{\rho})$ a bit like what you wish for, but these arethat object carries very little information, is known to exist only under specific hypotheses on the $\rho_i$ and typically requirerequires the previous knowledge of strong versions of the conjectures on special values of $L$-functions to be really meaningful.