Patches disabling some anti-features of Telegram Desktop.
makepkg -si
Or if you want to regenerate PKGBUILD for current patches in the directory:
make
You may also install a prebuilt package published in releases.
Download source code of Telegram Desktop and run commands from prepare(), build() and package() in PKGBUILD manually.
Enables saving media, selecting and copying messages in channels, which disallow doing so.
Disables restrictions for viewing and exporting private chats and channels you didn't join but are able to view.
Feel free to contibute patches and means of packaging and installation.
Killergram - Xposed module featuring some patches with similar functionality for Telegram for Android.