I have a friend, who, when depressed just stays in her house, doesn't answer the phone unless she knows who is calling and doesn't answer her door.
She didn't answer the door one day, not realising it was the police, so the PC went and got the, I don't know the name, mini battering ram thing.
Regardless of your reason for doing so, I detest the assumption that somebody at home should be expected to stop whatever they're doing and answer the door if an unsolicited caller 'summons' them by knocking or ringing the bell.
You could be depressed, ill, having a bath, going to the toilet, feeding/changing/comforting a baby, having sex, working from home, be right in the middle of something and concentrating - or just be having a duvet day, or wanting peace and privacy in your own home for any reason. Your home is not a public place.
I think it’s great and reassuring that friends / neighbours care enough to recognise that an absence by a neighbour/ friend merits a welfare check. I think of the sad cases where a small child has starved to death because nobody cared enough to report the mother’s absence.