Check out VSCode's "Ruby in Visual Studio Code" page [1].
Ruby LSP already does quite a bit and started gaining go-to method abilities last month [2], though it isn't complete quite yet [3]. It's build on Prism, so promises to be more robust than past attempts. Shopify has been moving fast on improving things here.
The Rdbg integration works great too [4]. Just add a `launch.json` and VSCode can hook into the very nice capabilities Koichi Sasada has been adding to the official `debug` gem.
Yes, with Solargraph. It uses type inference most of the time, and when it can’t guess the type, you can add YARD comments. Intellisense also works well (autocomplete).