> They are advancing, but incredibly slowly

Their tactics have settled to extremely-small infantry infiltrations across almost the entire frontline. Warfare has evolved and concentrated mechanized assaults have been abject failures for both sides; it's far too easy to mass fires than it is to mass maneuver forces (see additional commentary (1) at the bottom). Russia's ground strategy is probably the least-risky way for them to keep pressure on the defenders and husband their own resources.

> their lack of manpower is exactly why I think Europe should come to their aid.

Be the change you want to see in the world: https://ildu.mil.gov.ua/news/how-join-armed-forces-ukraine

(1) Normally I would blame both air forces for lacking the capacity to systemically disrupt the defender at all depths.....but if we look at the Israeli aggression against Lebanon, the Israeli air force has total air dominance and their heavy mechanized forces are still struggling to advance. FPV drones basically quadruple the range of every ATGM team at 10% of the price.