I will add Total Commander (for Android). While not FOSS (AFAIK), it is freeware, features dual panels and also supports SFTP/SMB/CIFS for copying from/to a NAS.

https://www.ghisler.com/android.htm

https://www.ghisler.com/tcandroid3.apk

https://www.totalcommander.ch/android/plugins.htm

Horoable mentions: https://kdeconnect.kde.org/

https://localsend.org/

And of course install everything with: https://github.com/ImranR98/Obtainium