Exist co-founder here. The Narrative Clip is on our radar, but seems to be more of a lifelogging/journalling use case. For now we're focused on making your data useful but we have had a few people ask about the possibility of a lifelogging/journal angle so that could be where we end up down the track, who knows...

Hi :) I'd love to have some high quality biofeedback tracked, in particular for measuring stress and concentration levels (in so far as either can be neatly defined).

Those metrics would be great to have. We already have a huge to do list of services to integrate, and I'd love to have some easily available ones like heart rate and blood pressure in there soon.