My 2018 does not work with the app. 2019 newer does. Trying to add to communicate with my car. Any workarounds? 3rd party adapters? I'm in the USA

 

I have not had a problem with Android Auto on my 2017 XF but it does have the In Control Touch Pro. I don't know if the other system would differ. I use the 'AAWireless Two' adapter so I don't have to have the USB cable hanging out, but I would expect a wired connection to work just as well.
It will drop signal at times, but as this is always in the same location I blame Bluetooth interference and not the adapter. I cannot find reference to Android Auto in the online manual for either version.
I know for the XJ there was a firmware update available that included Android Auto. Maybe the same for the XF?

 

Yes you can update your 2018 to work as the 2019.

 

I just updated my InControl Touch. This may be common knowledge, but I thought I would post it just in case.
When I used the start button to turn on the ignition and checked the software version of InControl for an update it would always fail or say I was on the latest as I couldn't get it to connect to my home Wi-Fi. If I tried I ended up in a loop about not having an account setup (Still waiting for Jaguar to remove the previous owners info)
This time I just powered up the InControl system from the volume power button. This allowed me to connect to my Wi-Fi network. No idea why this would be different, or if I messed something up the other times.
Once connected to the Wi-Fi I was able to check the firmware version, and it did identify there was a new version. I did wait for the download to complete before doing anything else, but I was able to drive and use the car without issue while the install took place. (I know some of the newer Jaguars require the car to be off and locked before they will update)
Maybe try this to see if there is an update for your car?