I was a bit slow on this one, but I finally disabled Google Maps on my phone! I've been using Organic Maps (https://organicmaps.app/) for a little while now and I've had a great experience. I just have two issues:
1) Unless I download Organic Maps from the Google Play Store, I can't use it with Android Auto when I'm in a car. I want to disconnect from Google, so this is not ideal.
2) It seems like @organicmaps is the official Mastodon account, but they don't have their website verified.
It only took a few minutes to copy the places I had saved on Google Maps into a note in #Fossify Notes (https://www.fossify.org/). As usual, I'm finding that plain text notes are exactly what I need and give me a better experience than these bloated corporate apps.