> when I have something to say about my day, there's nowhere to say it; no one on HN cares whether I fixed up the blinds or cooked pork steaks.

As someone who lives alone, two ways I address this aspect: talk to yourself out loud and to your pets like they're people, and also write these things down in a journal. Every night after I get into bed but before I turn out the light and fall asleep, I write a journal entry. Sometimes they're quite mundane, exactly like your examples. "I cooked a steak for dinner that turned out better than I expected" or "Tomorrow I'm thinking about making some bread." There's no pressure on length of entry, I fill anywhere from three sentences to a full page each night, but it helps fill the 'how do I communicate this minor accomplishment or discomfort that nobody else cares about' need for me.