Thanks for clearing that up for me regarding terminology. I had thought of namedropping you too by the way but decided against it as I haven't had that much contact with you. Anyway thanks for your input here.
I definitely am interested in exploring relevant existing games. I was unable to find very much in the way of a voluntaryist tabletop RPG (or even "ancap", though I wouldn't find my the general goals there super aligned anyway).
Those games sound like interesting case studies. What I'm interested in is a system without much more than physical or historical restrictions on users. By physcial I mean strength, skills, dexterity, etc., and historical restrictions like people who may know you in the wider world and have a claim to you, etc.
This was a big point in the original computer game design, to not give PCs things like "beliefs" or non tangible attributes and let that come out in RP behavior. In some ways that's anti-RP, or at least it makes things perhaps too unmoored so I would perhaps replace them with goals, aspirations, etc. which might be secret for a player but they'd be encouraged to keep them and could even use something like "inspiration" feature, as in DnD 5e rules.
I know that players will be interested in violent conflict being sensible even if they choose to not engage in it too much. To make a lot of assumptions about where we'll end up, my ideal game would have some people take on antagonistic roles for the sake of testing some of the ideological positions the "good" characters might take.