For personal agenda I use Apple Notes with basically just a huge list of things to do and events that are about to happen and I curate that list more or less non stop during the day. If something comes up and I'm with people and don't want to be rude and spend too much time on the phone editing things to be in the right order and have all the relevant info captured with them, I just plop a line at the top of the note knowing I'll groom it later.