Find widely known orgs that use the platform, the BBC comes to mind here. Search for other well known orgs to point out so you don’t just have one example. Highlight the fact that other platforms are cross linking to the fediverse (Meta’a threads for example) so a fediverse presence will give the city a presence on those platforms with no extra effort needed. Point out that Twitter has become an unreliable platform due to ownership change and that that situation could replay itself at any time on any centralized platform. Help people get Mastodon working on phones if needed - the official app is quite good. Basically just sell the platform as best you can, don’t go heavy on ideology and focus on practical benefits.
Emacs users be like