They have mostly wasted their railway infrastructure following the collapse of USSR.

RVR[1] car maker wound down, some tracks has closed down due to lack of use or excessive wear. They have some commuter trains and some coordinated cross-border train pairs. Russia to Kaliningrad also runs through Lithuania as mandated by international agreements. I don't think you can embark at Vilnus though.

There were Moscow-SPb-Tallin and Moscow-Riga sleeper trains for a long time, but COVID and lack of funding led to their demise, and now the war, too.

There was also Moscow-SPb-Helsinki "Lev Tolstoy" sleeper train of the same fate.

1. https://en.m.wikipedia.org/wiki/Rīgas_Vagonbūves_Rūpnīca

New/improved rail links are planned/in progress as part of TEN-T which will probably help

https://transport.ec.europa.eu/transport-themes/infrastructu... https://transport.ec.europa.eu/transport-themes/infrastructu...