This app was mentioned in 3 comments, with an average of 1.67 upvotes
Probably OpenSSH will be the best solution.
In CMD, use command:
sudo pacman -S openssh
And start it after install:
sudo systemctl start sshd
It should automatically open 22
TCP port to allow to make remote SSH connections.
If you want to connect from Android device, check Mobile SSH application.
> If you do not have a USB keyboard you can still connect to the WiFi network of your choice. You will however need to plug the Console into your router first and make sure to power it on.
For Windows: Bitvise SSH Client
iOS: Terminus
Android: Mobile SSH
> Host: retropie
> user: pi
> password: raspberry
> port 22
> sudo ./RetroPie-Setup/retropie_setup.sh
This will take you to a blue and gray screen. Keyboard down to the “Configuration / tools” and press Enter.
Go to option 835 wifi – Configuration Wifi and press enter.
Press enter to “Connect to WiFi network”.
Select your WiFi SSID (WiFi Name), press enter.
Enter your WiFi password. Press enter.
quoted from: https://retrotoledo.com/2017/01/08/how-to-connect-to-wifi-with-without-a-keyboard/
(formatted for reddit, cleaned minor mistakes)