There's a couple of ways you could tackle editing that depending on what your json looks like.

For example you could use the visual block mode (ctrl-v) and highlight to the end of the line using $ and then use A to edit the end of every line at the same time. That works with lines of different length.

Or you could use a regex inside of a block selection.

Or there's a multi-cursor plugin available for the same approach as you're currently using in VSCode:

https://github.com/terryma/vim-multiple-cursors

Vim Golf is an excellent resource for seeing how to efficiently edit things in Vim: https://www.vimgolf.com/