@Andreas , Based on my research, we didn't find a public sites which stores intunwin files. This can be because the requirement is different and the new version of the software is always updated.
From your description, I know we want intunewin file like Adobe Reader. we can follow the similar steps in the following link to convert the software to intunewin format and deploy it via Intune.
http://eddiejackson.net/wp/?p=29483
Note: Non-Microsoft link, just for the reference.
Hope it can help.
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