There is a lot of materiel in the pipeline. It just takes time. The first of the M777's arrived May 8. IIRC as of the 22nd of May, 12 operational 155mm howitzers had fired 1876 rounds. 4 of those 12 are capable of firing GPS guided munitions. I think they wanted to get them to the front as quickly as possible, and it was faster to go "old school" at first.
The ones moving forward now appear be M777A2 which have the digital fuse setting capability to fire the GPS guided munitions. There are also several thousand M982 Excalibur rounds going to Ukraine which are deadly accurate.
The training of crews continues and there are a lot of heavy weapons still to move east.
Also it sounds like the decision is made to provide the M270 and HIMARS launchers and GMRLS missiles, expecting to hear details next week. ATACMS not likely. GMRLS will give a 70km reach to UA artillery and hit within 3m.
Denmark's announcement to provide Harpoon can be an ice-breaker. Take away the fear of being the first country to provide AShM's to Ukraine. Norway and the UK have both talked about sending NSM- would be much faster to get in service and is a more modern system with the same role.
It's WW1 trench warfare right now. Putin is using the L/DNR conscripts to the clear trenches because no one in Russia will care if Ukrainians are killing Ukrainians.
Also looks like the push from Popasna has petered out.
Reports that a Ukrainian MiG-29 downed a SU-35S over Kherson. Might be that some of those "spare parts" have been reassembled...