How are iPhone users navigating new cars without Apple CarPlay?

Bluetooth connection, and Siri voice commands. (Same as the pre-CarPlay post-Bluetooth era.)

Here is how to: Use Siri on iPhone - Apple Support

Maybe create and invoke your own Shortcuts for certain custom tasks, if needed.

Aftermarket CarPlay infotainment system might be an option, given the budget for that.

What does Google have to do with anything? Are you saying your car has Android Auto but no CarPlay?

My last car did not have carplay. I got a dashboard mount for the phone and used Bluetooth. Siri can read messages, play podcasts, etc. If you have to interact with the phone too much to be safe while driving, pull over and do it.

There are 3rd party carplay displays available. I had one, and it worked fairly well. Because of how much space it took up, though in my tiny 2 seat convertible, and the fact that I didn’t like having a big honking piece of electronics exposed when I parked the car, I only used it on long road trips.

Traded that one in and bought a newer car with CarPlay in January. I have to say I’m now one of those people who won’t consider a vehicle without CarPlay in the future. Not unless something substantially better comes along at least.