It looks like they're still figuring out the transition :(
I just tried a Google Takeout export of the Timeline data, but it was an empty skeleton of the previous Timeline that just has a text file saying "You have encrypted Timeline backups stored on Google servers."
I have no idea where that actual backup is, either on the phone or on the server. There seems to be no way to access it anymore, lol =/
Anyway, nevermind my niche use case. Good luck with the app and excited to see how it comes out!