Migrations are very tough when you go offline-first. Cambria [^1] is an interesting read. For Instant, we are schemaless and think about offline more like a cache. In our case it's less of a problem.
Thank you! Having one of my projects died to it (lack of migrations, offline-first) I had promised myself I'll first solve that problem before writing a meaningful line of business code in a future project. :)
[^1]: https://www.inkandswitch.com/cambria/