I don't experience any issues using mapping apps on Android with microG instead of Google Play Services. Closed source navigation apps including Google Maps, HERE WeGo, and Magic Earth work just fine. Open source navigation apps like Organic Maps and OsmAnd also work with no problems.
Alternatively, if you prefer Google's closed source text-to-speech engine (that is preinstalled on most commercial Android devices), you can download Speech Services by Google through Aurora Store:
Most navigation apps come with their own voice banks for turn-by-turn navigation audio, and installing a text-to-speech engine isn't necessary for these apps. However, Organic Maps (which is a recommended app in the CalyxOS setup wizard) doesn't, and it relies on the default text-to-speech engine.
Thanks! I didn't know about RHVoice. I tried installing a couple others I found through searching F-Droid, but nothing worked. I just installed RHVoice.
If you're not sure whether an app is compatible with microG or a flavor of Android without Google Play Services, Plexus is a helpful database of crowdsourced compatibility ratings:
I don't experience any issues using mapping apps on Android with microG instead of Google Play Services. Closed source navigation apps including Google Maps, HERE WeGo, and Magic Earth work just fine. Open source navigation apps like Organic Maps and OsmAnd also work with no problems.