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

There’s also this one as 3D print solution with smaller filters.

https://www.oddcube.com/

https://www.youtube.com/watch?v=GpA7-EJpKWU

I have days where I am also a slave to this dreaded cycle… As others have stated: adding a bit of salt/electrolytes can help. It does for me. And apart from having to pee less, I reckon it is a good idea anyway, because drinking + peeing very much will likely have a negative effect on one’s mineral levels.

Excessive thirst/urination can be a symptom of diabetes. And I am sure there are other ailments related to it, so maybe next time you visit your doctor you might want to mention it. Hope you can get it figured out!