How would they put pressure on tech giants to do the same? Did other tech giants join the FLA and open its manufacturing lines to its auditors after Apple joined?
Foxconn is the one opening up in other countries with better conditions than local factories. They have factories in Brazil, Europe, India, Japan, Malaysia, and Mexico.
Again, how does leaving China improve Chinese worker conditions? They have improved conditions for their workers because they've stayed. Are you concerned about the workers or just want to clear your conscience?