If the Ukrainian national forces were involved, Russia would have already provided that evidence. If it could have been implied, Russia would have already done so. Pretty strong inferred evidence that national forces were not involved.
But let me point out the corpse in the room; a Muslim plane was shot out of the air. They will view it as a Russian action, no matter what the eventual truth is. They would not be able to imagine a weapon system like this outside of Russian hands, as that would be what their government would do.
Another 250+ martyrs have been made, and Russia will likely have another major terrorist attack on their soil because of it. And they know it. If there was a way to deflect that attack onto Ukraine or the West, Russia would have stepped up with that information. And that there were planes from Singapore Air in the region at the time, far less dangerous targets, points to very little direct Russian involvement.
To me, this looks to be exactly what early reports indicated; pro Russian forces using the toys they showed reporters the days before and hitting a non combatant.
With 20 something Aussies, 15 or so Dutch, at least one American, Germans, other Europeans, Asians, 80 children, that was flying from the Netherlands to New Zealand or someplace in Asia?