I like the idea of having more app filters!
SSO great idea.
When it comes to an "open source" filter, I think the open code based makes more sense, rather than looking at all add-ons or price. We are talking about filters on Cloudron App Store, therefore think the question is, "is the app actually installed from cloudron app store opened of closed?", not any add-ons people may choose to install later on.
Other options could be to have:
a Free Software filter for program without any proprietary add-ons
a "close sourced" filter for apps where the code of the base app is not available (i.e. that app actually installed from the app store)
a $ filter for program that require a paid license
Mainly I think we should NOT conflate price/money and license type / openness of source case. Take Teamspeak, for e.g., it can be used for free, on a free (as in free beer) license, yet it is proprietary software.
I think that whatever filter option we choose, the openness of the code that is actually being installed from the Cloudron App Store (i.e. without add-ons) is the thing that users should be made aware of / able to easily choose from. So as a first implementation of any filter, I thing the open/closed source filter would be the priority.
