My implementation for surround in visual mode.

mini-surround.lua

-- Surround
function Surround_with(start_surround, end_surround)
	local vstart = vim.fn.getpos("'<")
	local vend = vim.fn.getpos("'>")
	local start_column = vstart[3] - 1
	local start_line = vstart[2]
	local end_column = vend[3] - 1
	local end_line = vend[2]

	-- Skip whitespaces at the start of lines
	if start_column == 0 then
		vim.api.nvim_win_set_cursor(0, { start_line, start_column })
		local char = vim.api.nvim_get_current_line():sub(start_column + 1, start_column + 1)
		while char == " " or char == "\t" do
			start_column = start_column + 1
			char = vim.api.nvim_get_current_line():sub(start_column + 1, start_column + 1)
		end
	end

	vim.api.nvim_win_set_cursor(0, { end_line, end_column })
	vim.api.nvim_put({ end_surround }, "c", true, true)
	vim.api.nvim_win_set_cursor(0, { start_line, start_column })
	vim.api.nvim_put({ start_surround }, "c", false, true)
end

function Surround_with_input()
	local start_input = vim.fn.input("Surround with> ", "")
	local end_input = start_input
	if string.find(end_input, "<") == 1 and string.find(end_input, ">") == string.len(end_input) then
		end_input = "</" .. string.sub(end_input, 2)
	end
	if string.len(end_input) == 1 then
		if end_input == "<" then
			end_input = ">"
		end
		if end_input == "(" then
			end_input = ")"
		end
		if end_input == "{" then
			end_input = "}"
		end
		if end_input == "[" then
			end_input = "]"
		end
	end
	Surround_with(start_input, end_input)
end

vim.keymap.set("v", "(", ":lua Surround_with('(', ')')<CR>", opts)
vim.keymap.set("x", ")", ":lua Surround_with('( ', ' )')<CR>", opts)
vim.keymap.set("x", "[", ":lua Surround_with('[', ']')<CR>", opts)
vim.keymap.set("x", "]", ":lua Surround_with('[ ', ' ]')<CR>", opts)
vim.keymap.set("x", '"', ":lua Surround_with('\"', '\"')<CR>", opts)
vim.keymap.set("x", "'", ":lua Surround_with(''', ''')<CR>", opts)
vim.keymap.set("x", "{", ":lua Surround_with('{', '}')<CR>", opts)
vim.keymap.set("x", "}", ":lua Surround_with('{ ', ' }')<CR>", opts)
vim.keymap.set("x", "S", ":lua Surround_with_input()<CR>", opts)

I couldn't really get used to the keymappings of the surround plugin for vim/neovim, so I wrote this small implementation with everything I need. The keymappings are:

Mode	Key	Example	Description
Visual	(	hello -> (hello)	Surround with parentheses
Visual	)	hello -> ( hello )	Surround with parentheses, separated by space
Visual	[	hello -> [hello]	Surround with square brackets
Visual	]	hello -> [ hello ]	Surround with square brackets, separated by space
Visual	{	hello -> {hello}	Surround with curly brackets
Visual	}	hello -> { hello }	Surround with curly brackets, separated by space
Visual	'	hello -> 'hello'	Surround with single quotation mark
Visual	"	hello -> "hello"	Surround with double quotation mark
Visual	<	hello -> <hello>	Surround with angle brackets
Visual	>	hello -> < hello >	Surround with angle brackets, separated by space
Visual	S<input>	hello -> <input>hello<input>	Surround with user input. User input is read up until <Esc>. If user input is a tag (that starts with <) the selection will be surrounded with opening and closing tags (for example hello -> <h1>hello</h1>)