Is there a way for me to convert a Google Maps URL to an Apple Maps-friendly format so it opens in the correct place?
I might be in the minority, but where I am, Apple Maps offers vastly superior driving directions.
You can simply copy and paste an URL from Google Maps (either from sharing with the Google Maps app), paste it in the Apple Maps search bar and it will resolve the correct location.
Google Maps short URL (of the form goo.gl) won't work and will need expansion before proceeding.
I've created myself a Workflow (soon to be named Shortcuts in iOS 12) to expand the URL automatically. You can force-touch an URL going to Google Maps and use this Workflow with the Workflow share extension.
Not sure how you can do it in iOS, I can't find the equivalent command, but you can do it on the Google Maps web site in a browser then copy/paste the info to Apple Maps…
Apparently, Google doesn't want you to switch apps. There seems not to be any easy way to export a location in a format that Apple Maps can read it. I also have been fiddling with it and I even tried to make a Workflow, but without success. In the end, I found two moderately easy ways to do it:
Tap the "code+" to copy it to the clipboard.
Then go to Safari and paste that code to search it in Google. You should get a Google search results with a map at the top. Tap the map to open a full version of it and then you get normally formatted coordinates, that you can copy and paste into Apple Maps.
An easier way to do it, but that's requires the eventual purchase of a third-party app, consists in using Opener. It's a small utility that allows us to choose which app will open a given URL. Having the app Opener installed, all you need to do is share in Google maps and select Opener.
It will give you an option to open that location in Apple Maps, or in other supported apps that you may have installed in your iPhone or iPad.
It's the easier easiest and quickest way I managed to do it in iOS.
I have been searching and there is no easy way to extract the coordinates or anything other than the a Google map URL from the iOS Google Maps app.
I have to think that it is on purpose.
The “easiest way” so far is to type by hand the coordinates (viewable but not copyable from the Google Maps app)