Is it not possible to include an package from apt in the snap?
I found this thread there it is said:
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For (2), that probably means building PySide2 from source as a second part in your Snapcraft recipe, since there are no deb packages of PySide2 in the 18.04 repository that you could reference via stage-packages. It is in the 20.04 repository, but the kde-neon extension does not yet support core20 snaps
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Because now kde-neon can be used in base20 as experimental extension, how can I use it as a stage-package?