Debugging works for some languages, though it's not comparable to IDEs like vscode. It's also marked as experimental https://docs.helix-editor.com/keymap.html?highlight=Debug#sp...
Helix also has multi cursor, but probably not as intuitive when you are coming from vscode.
Helix supports many languages without configuration, except installing the language server.
GitHub actions completions should probably work through this json schema with a language server, at least I didn't configure anything and when I edit docker compose files, I have autocompletion and validation. https://github.com/SchemaStore/schemastore/blob/master/src/s...
Command palette - i don't know what you are using it for, but nearly every modal editor like (neo)vi(m) has a "command line" when pressing ':' where you can run helix commands https://docs.helix-editor.com/commands.html
With helix you can get most of the vscode features, except debugging, extensions and file management, though most of the extensions can be replaced with some other tools (depends heavily on what the extension does, can't be generalized). A plugin system is currently on the roadmap and is being worked on, but I don't think anyone could tell you when it's going to be ready.