Simple ToDo list (for android and mac)

I want a ToDo list that looks like Wekan basically. I have two concerns that might make it not work out though. I'm curious if there is a solution people know about (be that Wekan or something else).

First concern: I don't want to send my data to a third party second concern: I don't want to setup LAMP

I basically want an android app, and a mac app that is my TODO list, and they just share a file (say if it's sqlite). maybe the file is shared in some way, so it syncs between the phone and laptop. Is this possible? Does anyone know if something like this?