Chris and Morgan discuss an ethical framework Chris has been workshopping for the last few years, "An Ethics of Agency", with the foundation of maximizing agency "for you, for me, for everyone" and minimizing subjection. CW: Note that Chris talks about an incident involving them experiencing suicidal depression at one point.
Other philosophical systems mentioned:
Peter Singer's book Animal Liberation, and the argument for Equal consideration of interests. (Note that Peter Singer gets criticism from some disability circles; this is a good summary. In general it's our position to focus on "raising up" rights, including those of animals; pitting animal rights vs disabled rights need not be done in a society with as many resources as ours presently is.)
Amartya Sen, whose book Development as Freedom had a bigger background influence than Chris probably realized in its treatment of the agency of people as the primary index by which we measure a country's development
The GNU Manifesto. Search for "Kantian ethics" on the page. (Curiously its preceding sentence is described in an example that appears consequentialist! By the way, pretty much every decent ethical system claims that its foundation is the "golden rule", this isn't unique to Kantianism.)
The Free Software Definition. Also note the pun on another speech called The Four Freedoms.
A FOSDEM talk in 2014, The Road Ahead for Network Freedom, where "freedom for developers, but not for users" is mentioned as a phrase
Libre Lounge's subtitle: "a casual podcast about user freedom", including mentioned episode with Karen Sandler
Some talks in 2018 by Molly DeBlanc (and Karen Sandler) using the term "user freedom":
Molly DeBlanc has a wonderful article giving a personal definition of "user freedom"
OCap conference 2018, source of the mentioned dinner between Chris, Mark Miller, Kate Sills
Chris's ActivityPub Conference 2019 keynote, ActivityPub: past, present, future