I'm not so convinced.

It's mainly because the attrition rate should have entirely depleted the S-300 system in the first 6 months (2-3 per week during the main phase).

Ukraine is a big country and there were loads of missile attacks to defend. It's very unlikely it was able to move S-300s continuously into needed areas compared with manpads.

Yet it would have been a PR disaster if NATO admitted to supplying weapons to Ukraine before the invasion started. So MANPADs are implied to have sprouted like mushrooms in Ukraine...