Unfortunatelly it is no good framework to do something real in the Delphi + UniGUI. Lazarus has a good LCL that about totally compatible with the VCL framework on all platforms, and all code could be moved to Lazarus with minimal fixes. But in Delphi you have no VCL on Linux. You have only FMX, that even have no the TBitmap class and all apis if totally incompatible with the vcl. About all of code must be rewriteen. In the case of million lines it's a big chellenge. The Lazarus UniGUI version also not available at a moment.
Also I try to use CrossVCL. It seems to good replacemnt for VCL, and have most standard VCL classes in Linux (it is not free, but ok, it's not a big issue). But UniGUI could not be compiled at the moment with CrossVCL because part of modules are not open sourced and compilator returns error that unigui's modules could not be compiled with changed sourses.
And I don't know what to do next. Still waiting for now.