What's the Best Data Backup Mechanism for Indexeddb Based App?

All data is stored in the IndexedDB because it helps avoid sign up bullshit, and keeps it free. I want it to stay that way and avoid cloud if possible (at least at this stage).

I am looking for some advice on creating the backup mechanism that would let the user keep their data. Idk, something like emailing their json dumps or something.

In the future, the app will be wrapped with electron for offline usage.

The app is a kanban board. Tracks time of whatever is on the "In Progress" column. It has an invoice generator. I am making it for my own usage - freelancer with clients. It's a far from production grade, but it already works and it replaced the apple notes, clockify[1] and invoice kitchen[2] for me. I suggest you to be careful if you plan on using it, and keep the backup of your stuff until I implement some mechanism.

[1] - https://app.clockify.me/tracker [2] - https://www.invoice.kitchen/