The "wormhole" you linked is closed-source, perhaps you meant this one, which is open-source (and iirc came first, but presumably has a smaller SEO budget)
I've been hosting my own pairdrop for a year now, very easy and quick to share a file between my smartphone and laptop without digging out a usb cable.
Run both as Docker containers on a server at home. Syncthing keeps the files on your PC, Mac, and BSD systems in sync, and FileBrowser can point to the sync share and supply a convenient web UI for phones, etc. It works for me, it's kind of like a local Dropbox.
Syncthing does not need a server to work over the LAN, and I think you can set it to only use peer discovery over a LAN. You can disable pubic servers, but data sent through them is encrypted anyway.
Syncthing + KDE connect does a lot.
The only issues I have had is that I cannot ensure that both are always running on android.
Oh for sure, Syncthing absolutely works peer to peer. But I find it useful to have a central always-online hub for clients to sync to.
For example, imagine you save a file on your laptop then put it to sleep. You turn on your desktop and the file isn't there because the laptop is now asleep. Having a central 24/7 Syncthing server allows the share to always be available.
I like the wormhole-william[0] Go implementation of "Magic Wormhole" protocol on the CLI. There's a couple of compatible Android apps[1][2] in the F-Droid store and Rydmport[3] for your GUI loving friends.
I really want to like kdeconnect because when it does work, it works well, but in my experience it just has way too many bugs and seems to randomly stop working for unknown reasons.
What is the Gnome equivalent? If you mean GSconnect, that's an implementation of kde connect. I think kde connect has some CLI tools, but they're not super ergonomic.
For CLI stuff, I usually just run the python http server or woof and make a QR code with the URL.
KDE Connect allows you to send individual files both ways and also to browse files on your phone from your computer. It is also capable of sharing the clipboard and open link from one device to another, as well as controlling input (mouse and keyboard) from another device.
Personally, I use pairdrop for that. Though, if I'm limited to CLI, woof has an upload option (-U) allowing me to select a file from the phone. Don't know of an easy way to do that from the builtin http.server.
Secret chats don’t work between the desktop client and the app, so I would suspect that, like the rest of the messages, everything is saved on telegram’s servers in the clear.
In terms of differentiation, I have not explored much solutions available out there so can not comment much on that. About the encryption part, WebRTC communications over browsers are encrypted using Datagram Transport Layer Security (DTLS). All WebRTC sessions are encrypted.
https://webwormhole.io/
https://github.com/saljam/webwormhole