Kdeconnect is usually gonna go over regular wifi or ethernet. So that might go phone to ap to laptop, for twice the wifi hops.
Also means the speed is limited by the router, so modern phones would be slowed by an older access point.
Or by being far from the access point yet close together.

Sure thing!

Unfortunately it doesn't, Localsend relies on a WiFi hotspot or AP to transfer files, what I am trying to build uses WiFi Direct (aka WiFi P2P), these two are not interchangeable nor interoperable.

LocalSend doesn't use wifi direct which means your devices have to be on the same network for the transfer. WiFi direct is more like AirDrop -- "direct".

I find it really buggy, it often loses connection and won't connect to multiple devices at once.

Yes actually I have tried it and I use it to share text between my devices and receive notifications.

The file sharing feature though is unbearably slow.

That is for two devices that are both connected to the same network. If I understand what this program is doing (without actually trying it), it allows two devices to directly connect to one another via Wi-Fi to transfer a file.

With KDE Connect, to send a file from Device A to Device B, your file travels from Device A to a network router (and any number of network switches, etc. in between), then from the router to Device B. It has to make several hops across a number of devices to reach its destination. And both endpoints have to be connected to the same external network.

With this program, Device A and Device B create a direct Wi-Fi connection to each other and just send the file. One hop. Two devices. Direct. The devices are establishing their own ad-hoc Wi-Fi connection for the purpose of the file transfer.

Or GSConnect for gnome.

Through 2 things:

1. The answer is partly in the name, but there is no magic involved. Direct Share uses Wi-Fi Direct (also known as Wi-Fi P2P), which bypasses the middleman and connects the two devices directly to each other, potentially increasing the file transfer speed. However, it is only as fast as the slowest networking stack of the two connected devices. This is in contrast to almost all other solutions (like localsend) that rely on the two devices being connected to the same Wi-Fi network.

2. The other thing is deep integration with most file managers and desktop environments. For me personally, I believe that you should not need to open an app to send a file to your other device. You should be able to simply right-click on any file on your system, and there should be an option that says "Send to". It should not open the whole app. It should only open a mini window or a small window with only the necessary things you need to send the file, which is:

   1. Select the device you want to send to
   2. (Optionally) Click Send

That's all.

Bluetooth is slow as hell