The app itself is under the Apache license. However, it relies on Facebook’s React Native, which has two implications:
React Native comes with its own build process (which I’m currently struggling with), no idea of how easy it is going to be to get that on F-Droid.
React Native is made available under a three-clause BSD license, but with a particular restriction: the license becomes null and void as soon as the licensee in any way that Facebook is infringing on a patent held by the licensee. This may never become an issue, but the clause as it stands is controversial and possibly the reason why the license is not OSI-approved.
Given those two considerations, is there any chance of getting Jitsi Meet on F-Droid?
As long as all the source is freely available, and all the libraries that it uses are free software, it should be just a matter of getting it to build. The GPLv3 and Apache-2.0 license have similar patent clauses. I think most free software people are opposed to software patents.
There is a good chance that this app uses the proprietary Google Play Services GMS libraries, for example, GCM. Lots of realtime communications apps do.
As for the build, the process is literally like running a shell script in a Debian/jessie machine with the whole Android SDK setup. If the packages you need are missing, you could download them as part of the build recipe.
As for the Google libraries—it looks to me as if they are indeed not needed: I managed to build Jitsi Meet on my machine (which has the Android SDK but none of the Google API/Google Play packages). It works on my phone, which runs LineageOS without GApps.
Notice the author of that thread? The other post referred to the old multi-protocol Jitsi client, which seems to have been abandoned in favor of Jitsi Meet.
The other post referred to the old multi-protocol Jitsi client, which seems to have been abandoned in favor of Jitsi Meet.