I upgraded my Pixel 3a to Android Q beta 4 (released Jun 5). Tor Browser starts fine for me. This could be a device issue or perhaps the latest beta fixed the problem people are seeing.
I should clarify, Tor starts and connects fine but I only see a blank page when I try to browse. I'm not sure if this was the issue that was being reported.
I do see a play store review from a Pixel 3a user that says:
"doesnt work with Q beta. goes through a succesful connection with tor, then blqnk screen. no error message saying i am not connected or anything."
I'm trying to collect some logs now. There are some native libraries used within the browser that could also be affected by upgrading to Android Q.
Based on this info, I don't think we need to go down the JNI path just yet.
I've gone through more testing on this issue. Nothing specific to this problem shows up in the logcat. We don't have any Tor specific issue, everything is loading and running. The about:tor page is blank on start so I think this is some sort of rendering issue within the gecko view.
I downloaded Firefox 66 for Android and installed on a Android Q device. Firefox 66 does not work. Version 67 works fine, however. So it looks like we will need to wait until we integrate against at least version 67 before we can get Tor Browser working on Android Q.
Also, FYI, the native TorService work will eliminate this kind of concern entirely since it'll link and run Tor via the officially supported methods, rather than the UNIX daemon hack.