@haven I use Neovim using just the Julia lsp and custom code based on TreeSitter with VimSlime to send code to repl. If it helps: https://github.com/dwinkler1/nixCatsConfig/blob/main/plugin/04_treesitter.lua and for Julia https://github.com/dwinkler1/nixCatsConfig/blob/main/ftplugin/julia.lua
The treesitter code is based around the principle of root nodes you can define what is considered a root node (see Julia.lua) and when the cursor is anywhere in the code it will select everything up to but excluding the root node.