If Neovim or LazyVim is not showing .env file in the file explorer (snacks.nvim), it is very likely because Snacks does not show hidden files by default.
To show hidden files in NeoVim, press Strg H.
If the .env is still not showing then, but .env.example is, then toggle the display of gitignored files.
Files that are in .gitignore, are as well not shown by default in Snacks, the file explorer in NeoVim.
Use Strg I to toggle display of gitignored files.
Note that you need to be in normal mode, when pressing Strg I/H combination.