Sometimes I park my (manual) car and find that while I’m well aligned , I’m either too far into the spot (don’t always want to bait someone with my smol car) or not far in enough.
Assuming I’m on level ground (ie in a multi storey carpark), is it OK to put my car into neutral, let down the handbrake and push it a little? As opposed to firing up the ignition and driving it 50 centimeres?
Sure. Your car is designed to roll for hundreds of thousands of kilometers so 50cm won’t have any sort of impact on it at all.