I am deeply frustrated after spending the last days searching for a way to do what the title of the question says, but all I could find was IDA database -> Ghidra database conversions.
I have found Ghidra's "idaxml" Python plugins for IDA, yet those only seem to work for IDA -> Ghidra aswell, not like I got them to work at all since the scripts are for Python 2 while my IDA is on Python 3 and downgrading to 2 would break it far more to the point it's not functional at all. Additionally the XML export of Ghidra is lossy and buggy according to Ghidra themselves and some friends who did the conversion in the past.
So here I am with my last shred of hope. Does anyone know how to do this? It doesn't have to be from a GZF file by the way, WHATEVER the source format from Ghidra works, as long as it provides a functional and complete IDB at the end.