Is there a way for me to config the unit so it will use my phone's location service instead of using the GPS unit that comes with the conversion kit?
Just had the upgraded version of lx570 conversion kit installed for my 2018 yesterday by one of listed installers, everything works pretty well out of the box. Touch screen is a plus, intergration is really well done (mouse movement is smooth, all steering buttons works inside AA/Carplay, audio quality is great as it is using Aux, going reverse or adjusting volumn/AC will bring up native UI, I can go on for a while but I think you got the point).
However I also noticed issue with the GPS unit that comes with the kit, when I was using carplay navigation it is constantly having trouble locating my actual location, I went into the settings and use the GPS test inside the AppPlus and noticed that the GPS signal is within lower signal stregth range.