Can’t live without total commander ultima prime. Best filemanager suite packed with tools for whatever you might need.

• Listary

• activ’aid, an autohotkey ensemble

[SurvivalManual] (https://github.com/ligi/SurvivalManual)

There is an app for this. Works offline, available on fdroid and playstore. Covers a lot of topics and the manual is mostly based on military guidelines.

Never needed yet, but it feels good to have it.