You can use it using your browser with Office 365, no ?

It can also disable animation in the web browser. Some website can see this setting and disable some stuffs.

There is librelingo but, honestly, it’s far behind Duolingo.

The closest software I found is to use a flashcard tool (like AnkiDroid) and then search for an open deck of your language using AnkiWeb.

Doing so you get a similar experience than DuoLingo without the gamification and pretty UI.

It’s seem abandoned, no ?

This branch is 2951 commits behind signalapp:main

syncthing to sync my files on all my devices

Which tool do you use to re-encode everything to opus ?

I tried with ffmpeg and it works but I had many issues with covers.

Same. Plus, on local network, everything stay on the network.

I’m starting watch a movie on my PC, then move the movie file into a synced folder, na finish the movie 2" later on my phone.