This is kind of a stupid newbie question but once I have my display up and running and I'll be displaying the stats of my system on it alongside stats from Pi-Hole. Will I be able to use SSh from my Laptop and VNC viewer too? My display will connect using GPIO pins.
For SSH the good news is yes you can.
The physically connected screen has no effect on SSH and you can actually run more than one SSH connection to the Pi at the same time if you need.
In fact, a lot of SSH programs allow you to set the screen size per session. I normally run 132x40 characters as standard.
VNC is a different matter and it may depend on how the driver for the TFT screen sets its resolution. With VNC I have found the best way is to set a default resolution in config.txt using raspi-config (normally via SSH) before using VNC for the first time to the Pi.
This MAY clash with the requirements for your screen but without details of your screen I'm not sure.