Got rid of that dependency in the py3 version entirely. It's used to spawn processes and watch over the PIDs for what its worth.
Unlock wallet flow is a bit busted atm, have to fix it. I suspect the offline signing will throw some exceptions along the way. Nothing design related though, most likely syntax issues (Qt4 doesn't translate 100% into PySide2) and missing imports (I've been refactoring the massive qtdialogs file into a collection of smaller files, in part to get rid of the circular imports). I've signed offline transactions on testnet before but went through some more refactoring lately so I expect some cleanup ahead of me. Could be fixed sometimes in the coming week. That aside, the wallet creation dialogs are probably busted, same with comments (doesn't map over to the new wallet format yet), and the migration dialog from old to new wallets is thread bare.
Be warned, the build system isn't super user friendly right now.