I picked up a small Bluetooth adapter (
https://amzn.to/33xU8U5) for $15 that solves most of the problems. Everything works as expected (maps, music, audio books, Google Assistant, etc.). The only issue currently is phone calls. Since this adapter doesn't have a microphone, any calls will just be through the phone (mine automatically switches to speaker phone for this). It's not ideal and I don't actually get very many calls, but it could be better.
I may try pairing my phone to iDrive just for phone calls, and to the Bluetooth adapter for everything else. We'll see if I can get that going (I tried it briefly, but didn't have enough time to fully test it successfully).