Ukraine needs 1,000 of the old M101A1 105mm field howitzer, or very similar 105mm (L118, M119A3, etc). Because Ukraine needs to include the following type of bombardment, in battery:
https://www.youtube.com/watch?v=hAc1CnKqSyo
I think this is what could have helped them to defend - a light and fast pipe behind every blade of grass.
Too late for that now and today they need to go on a counteroffensive and need range from their artillery and they need tanks.
January 12, 2023
Soldiers of the 66th OMBr practice firing from the American 105-mm M101 howitzer
https://twitter.com/sovietarmyfan/status/1613507649076617217