tree-sitter still works. Many features are implemented in neovim itself. This project provides an easy way to set up parsers for various languages (including installation and retrieval of necessary queries), along with some quality-of-life features. You can just fork it, and it will work perfectly fine for the 0.12 cycle (barring any underlying parser changes), or you can fork the previous version on the master branch if you want to keep using 0.11.

Considering this is a very common plugin in the neovim ecosystem, it will probably get forked and maintained by someone else, like null-ls was forked into none-ls.