Best way to have mobile devices synced to PC

[Giuseppe Chillem]

Hi,
I have a big library that does not fit on google drive (and I don't want to publish it). I wish to tag some files in Calibre and have them synced on the remote folder(s) of my android devices (different folders based on personal choice). Later should be used on MoonReader+

Are the the following scenarios possible ? and how ?

When devices are all on the same network I wish to export files from PC to both devices.
When devices are on another network (cellular..), you can start "sync" from the PC and files will be transfered to the remote directories via some tunneled sync services. No intermediate permanent storage like google drive.
A local android APP could connect to calibre server locally and sync PC tagged files from the user.
A REMOTE android APP could connect to calibre server REMOTELY and sync PC tagged files from the user.
A local android APP could connect to calibre locally and TAG for DOWNLOAD from android and SYNC.
A REMOTE android APP could connect to calibre server REMOTELY and TAG for DOWNLOAD from android and SYNC

Thank you in advance