They could, I suppose. Russia is in an untenable position right now. Helping Iran would jeopardize that further. Financially, they have issues. Major issues. Committing resources to Hamas and Hezbollah would strain them further. It would also increase the risk that NATO or another iterative western alliance would get involved. Russia does not want that right now. They can’t risk that. In short, I’d be surprised if russia would be willing to offer much help and if they did that it would be sufficient to alter the balance.Russia might back up Iran though. Which makes things complicated.
Which also means it’s in the world’s best interest to keep Ukraine in the fight. Limits the resources Russia has to give Iran.
I think the primary danger with Russia would be providing material for a tactical nuclear weapon to Hamas or Hezbollah. They’d do it in such a way that it would be difficult to tie back to Russian state actors. Even that would be fraught with risks though. The degree of surveillance currently would make that quite difficult to execute.