The G-1, G3 and G5 were all pressurized...
"If" it was from a pressurized variant...I doubt it was G-1...most likely G3 or G5.
In addition...many pressurized features were on standard Me109's (canopy features, lack of vents, cowlings with bulges for compressor, etc.) ...so simply having those screws does not make it 100% from a pressurized Me109.
Mike