This can be done with Nazca in the following way.
When reading in the gds file, specify scale=0.1 as argument for load_gds. That ensures that the objects will have the intended size.
When writing out the new gds file e.g. with export_gds, the default resolution of 1 nm will be used, which means you’ll loose the 0.1 nm (0.0001 um) precision.
If you want to keep that resolution, you have to specify the following before exporting:
nd.gds_base.gds_db_unit = 1e-10
nd.gds_base.gds_db_user = 0.0001
Other values can be used as well, but db_unit / db_user has to remain 1e-6 because the internal unit in Nazca is 1 um.
All of this should be used with care, so know what you are doing!