Adding a custom tooltip to a plot on hover

[chaz23]

I have a large dataset that I'm visualising as a scatter chart using vgplot. I'd like to add custom tooltips on hover. I know that I can add tooltips via the "tip" mark, but that doesn't really cut it for me. Some of the implementations that I've seen people using for Observable Plot like this don't seem to work with vgplot. Would anyone have any suggestions / code they could share on how to go about this? Additionally, is there a way to get the selected point / bar / whatever that is hovered on, rather than clicked? Many thanks.