I think vscode has definitely come a long way since it first dropped several years ago. You can definitely get auto complete, goto, lining, etc. Via the LSP framework, so all those things should work for python and c with some plugin installs and maybe a bit of configuration. The built in debugging support is also really nice.
Neovim is basically the same as vim in terms of its editing modes. Vim and neovim use a action -> select paradigm eg. To delete a word you would type d (for the delete action) then w (to select the word). Helix uses a select -> action paradigm so to delete a word you would press w then d. One of the nice things about this is you can see what text you'll be operating on before you actually perform an action. Helix also supports multiple cursors, which can be more familiar if you're used to sublime, atom, etc. Both have support for LSP so you can basically get code intelligence on par with most IDEs for many languages. Helix is generally a bit easier to configure if you're just using the base package, but isn't as customizable and doesn't support plugins yet.
If you want to check out neovim I'd recommend using a pre-built configuration like Lunarvim or Lazyvim these are just configuration distributions that take a lot of the legwork out of bringing neovim up to par with modern editors. Think of it like copying someone's dot files.
In the blog post, the author mentions using shim programs to translate between things like tree sitter and kakoune, how many of these sort of things do you use in practice, is it difficult to manage them? The nice thing with neovim compared to a setup like this is that I don't need anything installed aside from git and the editor itself.