Before the high mobility wheeled version (HIMARS) was fielded, the USA and several of our Allies fired the exact same rockets from the heavier tracked M270 MLRS. When it comes to firing those pods of rockets, both of those vehicles are interchangeable (as also is the wheeled South Korean K239 Chunmoo, that Poland is buying).
As far as I have heard, only the USA has given the Ukraine wheeled HIMARS, but the USA and some other Allies have also given some number of additional tracked MLRS launchers. I don’t know how many they have, however.
Several countries have increased their orders for new HIMARS, and the company is increasing production. Poland wanted to buy about 500, but delivery was so backlogged that they ordered 200 HIMARS, and 300 Chunmoo launchers instead.
Poland will mount them on domestically produced trucks, and has established a HIMARS repair depot. It will likely be a joint HIMARS/Chun Moo facility. They also acquired license to produce 2 of the Korean rockets, a 239mm GMLRS and a 600mm ballistic missile that looks like an updated ATACMS. Apparently the pods are physically and electrically interchangeable between the various launching systems.