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The only two requirements are the Rofi application launcher and the nmcli utility which is provided through net-tools. For information on installing these features, please refer to the links below.

Rofi application launcher - https://github.com/davatorium/rofi

nmcli - https://www.liquidweb.com/kb/how-to-install-and-configure-nmcli/

With a little bash scripting and use of nmcli, it's quite easy to pull together a list scan and connect to a network. First we'll write a script that utilizes your network card's scanning feature to display a list of available networks within proximity. Second, we'll create another prompt that asks for password input. Feel free to create your own themes or alter the ones I've written below. 

~/.config/rofi/scripts/networkselector.sh

#!/bin/bash

networks="Available Networks: "
allnetworks="nmcli -p -f ssid,chan,rate,signal,bars,security d wifi"
passprompt="Password: "

# List available networks
options=$($allnetworks | rofi -show -dmenu -i -p "$networks" -theme /$HOME/.config/rofi/custom_themes/show_networks.rasi)
ssid=$(echo -e $options | awk '{print $1}')

# Get Password
passinput=$(rofi -show -dmenu -i -p "$passprompt" -theme /$HOME/.config/rofi/custom_themes/password_input.rasi)
password=$(echo -e $passinput | awk '{print $1}')

# Connect to network
ret=$?
if [[ $ret -eq 0 ]]
then
  nmcli d wifi connect $ssid password $password
fi

*Note - after creating the 'networkselector.sh' script, remember to make it executable.

chmod +x networkselector.sh

Finally, we'll want to create two separate Rofi theme scripts; One for displaying available networks and another fhat accepts a password input. I have mine named "display_networks.rasi" and "password_input.rasi" and placed them in a Rofi Themes folder.

~/.config/rofi/custom_themes/show_networks.rasi

configuration {
  show-icons: true;
  modi: "dmenu";
}

* {
  hide-scrollbar: true;
  background-color: #000000;
  text-color: #FFFFFF;
  padding: 2px;
}

window {
  width: 60%;
  height: 50%;
  transparency: "real";
}

prompt {
  enabled: true;
}

entry {
  background-color: #282c34;
  padding: 0.5% 0 0 1%;
}

listview {
  cycle: true;
  spacing: 0%;
  dynamic: true;
  text-align: center;
  padding: 2% 4% 0% 4%;
}

element selected {
  background-color: #282c34;
  text-color: #fac033;
}

~/.config/rofi/custom_themes/password_input.rasi

configuration {
  show-icons: true;
  modi: "dmenu";
}

* {
  hide-scrollbar: true;
  background-color: #000000;
  text-color: #FFFFFF;
  padding: 2px;
}

window {
  width: 20%;
  height: 10%;
  transparency: "real";
}

prompt {
  enabled: true;
}

entry {
  background-color: #282c34;
  padding: 0.5% 0 0 1%;
}

listview {
  cycle: true;
  spacing: 0%;
  dynamic: true;
  text-align: center;
  padding: 2% 4% 0% 4%;
}

element selected {
  background-color: #282c34;
  text-color: #fac033;
}

Assuming all paths are correct and your file is made executable, you're good to go. Easy! Run the file with by simply "./networkselector.sh" or "exec <path to .sh>" bound to your favorite shortcut key. Because I use I3WM and polybar, I have it as a click function on the bar itself. If you're interested, locate your polybar config file and paste in:

[module/networkselector]
type = custom/text
content=|         |   ;Font awesome icon of a network
click-left = exec ~/.config/rofi/scripts/networkselector.sh