The bulk of the Mastering Emacs blog is a decade old at this point, but its philosophy and the information it provides is still very relevant for any graybeard wanting to get up to date.

I'm a pretty conservative emacs user, partly because I don't want to spend time tinkering to get things to work consistently across Windows, ubuntu, and mac os -- all of which I use daily. My most "modern" adoption is probably using lsp and eglot with various language modes, notably golang and rust.

Should I consider adding tree-sitter into the mix?

There's a lot of Emacs information on the internet, and your agent has been trained on it.

It’s already built in! C-h n view-emacs-news