Whitenoise by nostr:nprofile1qyfhwumn8ghj7ur4wfcxcetsv9njuetn9uq3jamnwvaz7tmswfjk66t4d5h8qunfd4skctnwv46z7qgewaehxw309aex2mrp0yh8xmn0wf6zuum0vd5kzmp0qy3hwumn8ghj7enfd36x2u3wdehhxarj9emkjmn98ankcmmzv9kr6ctvdshsz9nhwden5te0wfjkccte9e4x2enxvuhxv7tf9uqzq9eemymaerqvwdc25f6ctyuvzx0zt3qld3zp5hf5cmfc2qlrzdh0t6lycm uses strong encryption for privacy within groups. Currently kind of a signal alternative but it could scale to larger groups. However, there is always a social trade off to be aware of. The larger the group, the less trust exists within the group, and the less consequential privacy on the technical level is.
I also think that the relay requirement is an acceptable trade off, since large groups are usually going to have a sufficiently committed admin that will be motivated to run a relay, while smaller groups can thrive in a more informal encryption-supported scenario. The relay requirement may actually be a beneficial barrier to entry that discourages insufficiently motivated would-be community organizers from starting.