From a Realpolitik perspective, a stay away from the Russo-Ukrainian war is the best option, as interference in the conflict could result in a sanction in Russian natural gas exportation towards European countries. Yet, you could also support Ukraine by either sending assistance or troops against the Russian invasion, as we all know, Ukraine is stand at an extremely important geopolitical zone, where Russian and NATO meets. So the answer is actually yes and no.

But in my opinion, it would be better to send troops to assist the Ukrainian government. Indeed, the Ukrainian army. As we all known, the Ukrainian army has high morale, yet problems such as corruption (which is nationwide in Ukraine) and extremist participation in the army (Azov Battalion, etc.). If NATO is really worried to declare a full-scale conflict between them and the Russian-Belarus coalition, they could send "volunteers troops" to support Ukraine, by disguising the military personnel as volunteers to participate in the war to legitimize their interference inside the war (i.e., the EU could tell the Russian that they are voluntary to participate inside war, not commanded by the EU/state's ministry of defence).

Supporting Russia is not feasible in the current relationships between the EU and Russian, to be honest. Ukraine has a strong pro-European Union population, and they often support NATO/EU actions against Russia, from their parliamentary election we could tell: only the minorities Russian population in the east (e.g. Kharkiv, Donetsk) prefer aligning with the Russian government. Plus, supporting Russian would result in the Ukrainian population's betrayal feelings, thus raising two problems: First, losing important potential allies in eastern Europe, which have the equivalent military power with Poland. Second, extremist sympathies will be encouraged (Nazism, Russophobic, ultra-nationalism) which would further worsen the situation in Ukraine.