There doesn’t seem to be a parser for sh because :TSInstall sh throws. (assuming you use nvim-treesitter plugin). I got your example to highlight properly by moving the scm file to ~/.config/nvim/after/queries/bash/injections.scm and doing :TSInstall bash, :TSInstall awk (even though I kept the same shebang and :echo &ft shows sh).
By the way, since you just joined, this forum is unofficial, see: