Yeah that's a good idea. The prep before leaving came about because I already have a habit of making sure I have music or podcasts downloaded since I live in a rural area that doesn't have good enough service for streaming. I still think its a good habit either way.
Switching map apps is tough for all the reasons you mentioned and more.
I'm exclusively using CoMaps for navigation but doing a little extra work before hitting the road by assuming the destination is wrong and double checking it and updating OSM if needed.
For my partner, this would be a deal breaker and she would be back on gmaps so fast. So instead of going head on into this, we settled in MapQuest which isn't perfect, but doesn't accidentally take her to the wrong town and provides traffic information and road closures at least.
I think it's worth it in the long run to not be spoon feeding my location and shopping habits to Google 24/7 while dealing with ads in a maps app.
Good luck to you!
Is this satire?
Thanks for sharing!