Based on @maarten 's post https://blog.nlnetlabs.nl/what-i-learned-in-brussels-the-cyber-resilience-act/ I think the only people listed in my example that would be at all regulated by the #CRA would be the last one: "contracted contributors". It sounds like they might be considered "open source software stewards" with obligations under Article 17a depending on whether the #EU considers F-Droid as "intended for commercial activities"
https://www.cyberresilienceact.eu/the-cyber-resilience-act/
My guess is #Nextcloud/#Ubuntu would be considered commercial while #FDroid/#Debian would not