Oh you don’t have to tell me. I’ve been the talk of the town lately when it comes to disliking being limited to installing software exclusively from the store. 
Still, the PureOS Store (actually, it’s GNOME Software, to be more accurate) offers a non-command line way of installing Signal. While I agree that using command prompts can be fun, my goal is to try and find ways for Linux to be used within the GUI itself thus allowing me to encourage non-techie friends and family to switch to Linux. As you can see from my previous post, it’s not been easy. 