F-Droid is like package maintainers for Linux distributions. You have to trust them if you want to use their pre-built binary. However, some app builds are reproducible. Check the doc for more info.

Of course, but v1.x only supported gocryptfs. Also, new encrypted file systems may be added in the future.

DroidFS can open existing volumes. Just click on the “+” button in the bottom right corner, then on the folder icon, and then select the volume directory.

To type with only one finger, there’s 8Vim.

:help i_CTRL-H

<BS> or CTRL-H  Delete the character before the cursor (see i_backspacing                                                       about joining lines).

What about DroidFS?