I got this one:
https://www.amazon.com/dp/B09ZQJXWVW?psc=1&ref=ppx_yo2ov_dt_b_product_details
Works great!
The LTE modem is completely optional. The CarlinKit CarPlay dongle is necessary to provide CarPlay functionality.
I use this one and it works fine:
https://www.amazon.com/dp/B09ZQJXWVW?psc=1&ref=ppx_yo2ov_dt_b_product_details
If you don't have the LTE modem, you lose the "Premium Connectivity" features while using CarPlay, but I don't find that to be problematic since I just use maps from CarPlay and it works great (Apple Map, Waze, Google, etc).