My own response to your question is that ethics have to circle back iteratively between concept and practice as each shifts in response to the other. Perhaps the distinction between ethics and regulation or law is useful here, with the former being to do with an evolving set of values, and the latter being to do with their being made concrete and having punishments for violation attached….

It was interesting to see how Pearltrees works too.

Your questions around when ethics should be developed are really interesting. It seems to me that waiting for users risks things being developed without any ethical consideration, perhaps hard-wiring things that cannot be changed later on down the line. However, work in the research and development stage is often not very public, so the debates that can be had are perhaps limited to certain bodies.