I played around a bit with hledger, but ultimately did not see a reason to switch from ledger. I don't remember if I ran into any issues, but at least they are not totally compatible.
I very much doubt that, since Google removed the call recording APIs. But if someone can tell how it would work on recent Android, I would love being proven wrong.
You are arguing for selective encryption, but I can't really find any technical argument in your comment.
Whether we are speaking of encryption at transit or rest, there's a general consensus that encrypting everything is best in every way except possibly performance for select cases.
For example, it allows hiding (meta)data about the really important bits, and with computers it's really difficult to tell which bits of (meta)data could be combined to abuse. Tampering is a consideration as well.
*your