@squirrel I used to use BTSync, before it went payware, as a nearly-perfect drop-in replacement for dropbox.
But sharing from explorer to friends, you only have a few options:
1. A 3rd-party service (DropBox, OneDrive) which hosts the file for you but anybody can get it over HTTP.
2. Host your own HTTP server (Nextcloud, apache) and deal with port forwarding, NAT, etc.
3. Have your friends download an app and sync a file/folder to them (Librevault + dozens of others)
maple classic™ 
@gdorn already got nextcloud set up, thank you https://nc.maple.pet/index.php/s/WenHAjW40BfroYL
@gdorn all i did was use the ubuntu snap package so i'm sure it's unoptimized but at least it works
@squirrel Nice. I tried setting up #nextCloud on my linux VPS and it was rather painful. And I even did PHP development for five years early in my career...
Maybe my mistake was attempting to use Docker?