We got on well with NDN at the start 5 years ago but quickly learned they liked a gossip so distanced ourselves as it sometimes felt like you were being interviewed for info so it could be passed on rather than just chat. They do it with everyone on the street and I've seen other neighbours hide to swerve them. They are nice enough, but absolute curtain twitchers.
Over lockdown (it's been one long year of lockdown where I am) they have been doing my head in. So noisey, nosey and plain weird.
Like every one else during lockdown, we did some well needed work on our garden. Just us, no workmen. NDN suddenly decided he wanted to take our bins in and out for us all of a sudden. I was WFH one day and caught him peering in the bin and then having a wander round the garden. I called out and asked him to leave them, he was very sheepish. They then suddenly started doing similar work to their garden having literally not spent more than 5mins in it in the 5 years we've been here. Over summer after the work they still didn't spend any time in it, just stayed in the house all the time?!
My DH has a company car. If his is in for repair or he's asked to change, we always get a message asking if he has another new car. There are no issues with parking so it is just for noseyness.
If a letter or parcel gets delivered to them accidentally, its always slightly tampered with before it gets to us. I've heard them ask the postie if anyone on the street isn't in to give them a shout as they are happy to take it 
A neighbour further down congratulated me on my pregnancy quite early on before bump. NDN had told them. NDN wasn't told, they seen a highchair box in our conservatory.
Their path is on the side of the garden next to our boundary, they literally cannot come or go without staring in the windows the whole time.
Our house is currently for sale (well offer accepted now). We didn't tell them in advance, they are literally going to the bins every time they hear my door in the hopes of catching me. I can tell its driving them mad not knowing. No sold sign as yet. AIBU not telling them?
I'm sort of enjoying getting back at them in a mild way tbh. Probably makes me a horrible person...but to anyone who doesn't think IBU, is there any other ways to mildly torture a curtain twitcher neighbour?