Possible is
share the Delphi obj-Files with the gcc and with other Delphi-Versions.
Impossible is
to share Delphi-obj-Files with actual Visua-Studio-Projects. The reason is quite simple: the coff-Format has information included which is not available in the obj-File-omf-format which is produced by Delphi and CBuilder. The way to include Delphi-Code in VST-Projects would be as
dll or as seperate exe.