nvim-config VS nix-home

I am trying to create a new nvim config and move from coc.nvim to native LSP but there are a few problems with my auto completion. I am sure these can be resolved relatively quickly but unfortunately I dont have any skill in writing or reading lua or vimscript. All the important files (init.vim, ccls.lua, compe-config.lua, lsp-config.lua) are here. The first problem is that even though I set single_file_support = true in my ccls.lua, the autocompletion only works when for example a compile_commands.json is present (can be empty too). The other problem which is probably just bad configuration is that is used to cycle through the autocomplete recommendations but whenever there are none I cant use as normal key just to write a tab.

Not exactly. I add them to programs.neovim.extraPackages, so they are only available to neovim and do not clutter my PATH. You can reference my config if you wish.

I do some C and C++ in neovim, but I use clangd instead of ccls. My config.

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