The LM will never sell good as a business point if they even wanted to get it in USDM, in other words the business case for it is not feasible in USofA, and if they even want to make it, they will start by the next generation Sienna and if the sales grow up they may add the LM
For what it's worth, if we read the trademark tea leaves, there is no U.S. trademark for UX 300e, whereas there are for LM 300h and LM 350. In other words, we're more likely to see the LM than the electrified UX in the States.
Having said that, I totally agree with
@maiaramdan that an LM for North America would be an offshoot from the upcoming 4th-gen Sienna, and not the just-introduced-in-China first LM. In fact, I suspect that this initial LM is simply a stopgap until a more proper TNGA-K Lexus LM can be engineered. The whole situation reminds me of Lexus' origins, when the Toyota Camry Prominent / Vista was hastily pressed into service as the first Lexus ES for 2 years until the more properly Lexus 2nd-gen ES (Toyota Windom) was ready.