I don't live in the US, and at best the concept is very rare here, and I don't like the idea of it, but that sort of thing is exactly what I would like.
Flying a flag (why?!) has much more impact (probably negative) on your neighbours than it does (presumably positive) you.
In the UK flying a union flag (residentially) would be extremely unusual - I'm aware of one, not where I live, and indeed it attracts scoffs and eyerolls - you do see England flags (St George crosses) more, particularly at certain times of year or certain years; that's more a signal that 'I am a football fan' than of patriotism, though.
Maybe that biases me against them in general. But even for things I do 'support' in some sense (I noticed a Ukraine flag covering a garage door recently, for example) I don't want a flag waved at me, and I wouldn't want a neighbour that did that.