async fast minimalist plugin make format easy in neovim: Takes on somewhat of the role of null-ls by integrating automatic linting and formatting into your neovim flow. Has a smaller selection of built-in tools (but can easily be extended with custom tools, has an example on the github page).

Unfortunately does not yet have an equivalent to null-ls-mason which would allow automatic installation of any missing linting/formatting tools through mason. That's the real stumbling block for most plugins replacing null-ls in my case.