Previously, I had installed PX4 Firmware, ROS, and Gazebo using:
wget https://raw.githubusercontent.com/PX4/Devguide/master/build_scripts/ubuntu_sim_ros_melodic.sh
bash ubuntu_sim_ros_melodic.sh
I believe these two lines install all the packages needed for ROS and whatnot and I just needed to install python 2.7 because I am running ros-melodic. However, I had tried to install anaconda and then I tried to import the needed packages (rospy, std_msgs, geometry_msgs <- couldn't find geometry_msgs), but it was running on Python 3.8. I decided to uninstall anaconda in the end because I keep hearing that it is difficult to work with ros in a conda environment. Since I already have python2.7 on my machine for some reason, I just went ahead to create a python virtual environment instead and there is a lot of tutorial on how to do this anyways.
First I created a ros workspace with catkin
mkdir -p drone/src
catkin_make
cd src
catkin_create_pkgs bigdrone std_msgs geometry_msgs rospy
I open Pycharm-Professional and set the interpreter from drone/venv/bin/python. Now I tried to import my packages again, but all of them are missing. I thought maybe it is because it can't find the packages because it is a virtual environment, so I switched to the python in /usr/bin/python2.7. The packages I needed are still missing but I do have access to some like rosdep and whatnot. In addition when I simply run on the terminal:
python
>>> import rospy
>>> import std_msgs
>>> import geometry_msgs
Everything seems to work just fine for some reason.