I just noticed your requirement for no Kotlin and libraries. I'm still posting this because they are otherwise pretty simple and solid apps.
Some examples available on F-Droid I've been using for a long time:
- Fossify Gallery
- Fossify Calendar
- Fossify File Manager
- Binary Eye supports reading/creating QR/bar codes and other formats
- Aegis Authenticator
- Fossify Audio Recorder
- Material Files supports SMB, FTP, WebDAV
Fossify is the continuation of Simple Mobile Tools, which sold out out [1]. They also have Phone, SMS, Clock, Audio Recorder apps, and more but I prefer the default GrapheneOS apps.
Some examples available on F-Droid I've been using for a long time:
- Fossify Gallery
- Fossify Calendar
- Fossify File Manager
- Binary Eye supports reading/creating QR/bar codes and other formats
- Aegis Authenticator
- Fossify Audio Recorder
- Material Files supports SMB, FTP, WebDAV
Fossify is the continuation of Simple Mobile Tools, which sold out out [1]. They also have Phone, SMS, Clock, Audio Recorder apps, and more but I prefer the default GrapheneOS apps.
[1] https://github.com/SimpleMobileTools/General-Discussion/issu...