that makes me wonder if it would not be an interesting idea to have a plugin that points to a known proxy and you register your host with it. then the operations cost is low, a single plugin can be released, and you control the server and data. just a random thought (typing on mobile with no spelling check, please excuse typos).
A password manager really needs to be a high-availability service -- it should work even (especially) when AWS is down. Since our service (intentionally) does not cache secret data on the client, running a proxy is not substantially easier than running our service. Plus we'd have to write this proxy :)
