Synconizing mobile app to desktop

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Just looking for some expert direction on things to research to achieve the following.Note i am just learning python but have programmed some in VB. I want to create an app. that runs on either iOs or Android and desktop. I need to update/sync. data in a relational db. I was considering SQLite as the db, use SQLiteStudio to aid in building tables and dependencies, use SQLAlchemy for mapping to db, and Kivy to create mobile GUI.

What exists to synchronize mobile to desktop?will the same work for both iOS and Android?
Do i have to use TKInter for the desktop GUI and Kivy for the mobile GUI?
What other major hurdles do i need to consider on the onset?
thanks for any input.

[Larz60+]

I wrote a tutorial on the entire sqlalchemy ORM process, from obtaining data to sqlite database creation.
The entire tutorial can be completed in a few hours, and is located here: https://python-forum.io/thread-24127.html

Kivy can be used for both mobile and desktop apps, I suspect that it can be programmed to work on both iOS and Andriod, but not sure of this.
Googling 'coding Kivy to work on both iOS and Andriod python' brings up several videos and blogs on the subject.

I work mainly on Linux platform, so not familiar with syncing with (windows) desktop

[hammer]

Thanks so much.