If anyone is looking for this in 2025 - check out this control from MESCIUS ComponentOne:

WinForms MultiSelect Control.png

It's called MultiSelect and it works as both a checked listbox and a comma-delimited tag editor. See more here https://developer.mescius.com/componentone/winforms-ui-controls/multiselect-winforms-list-control or get the nuget package called https://www.nuget.org/packages/C1.Win.Input.MultiSelect