This is for you as much as this is for me, since I want to remember some stuff I do and the blog sometimes serves as a public knowledge base.

Regarding 27.1, there's plenty of great resources here and here, so I won't go over them.

Simple installation considering you have Development Tools and TLS libraries installed for your distro:

wget http://ftp.gnu.org/gnu/emacs/emacs-27.1.tar.gz
./configure --with-json
make
make install

I'm only adding native JSON support since it's the number one (or number two after language servers) feature in Emacs 27. Since the loading order in 27 changes, I'm adding support for previous versions with the following in my .emacs.org file:

(when (< emacs-major-version 27)
  (package-initialize))

Additionally, I had to run go get golang.org/x/tools/gopls@latest in order for gopls to not crash. Other than that, it seems like this version hasn't broken any other elements of my set up; but it might still be a little bit too early to tell!